- Glenn Villpu

Your choices determine your style, not the other way around. It's not a very good idea to be concerned with "your style" at this point of the learning curve. You can't make interesting artistic choices if you haven't got a sufficient amount of techniques and concepts and tools to choose from. It's a much better idea to be concerned with expanding your range of techniques and tools and ideas so that you can make more interesting and creative choices later.
It would be a different story if you were in desperate need of a job, had no time to devote to expanding your skillset and absolutely had to cash-in on the stuff you can already do.
Of course, choosing your career path has a lot to do with what your tastes and your deep-down-motivations are; and these things usually pop up more or less in your style right from the start. But I don't think your current style can be used as a good criterion for career choices yet. At least not according to your description of your own style, which is mostly about skills and techniques. I have no doubt that if you learn properly and continuously challenge yourself to step out of your comfort zone, your skillset will expand very rapidly and you will, as I said, be able to master and/or develop the style(s) that you want for the career path and great artistic goals that you choose.
The questions that I would find more interesting concerning career and study choices are not linked to your current style.
The most important question to ask yourself is do you really know what the job(s) you are considering entails?
It's pretty clear to me that you love highly detailed, lively, crowded, atmospheric and eye-catching environments. But that's not all there is to being a professional environment designer. I'm not sure that you realize that. One of the reasons why I say that is that of the 6 artists you showed me, only n*kim and tomiokajiro are professionals and none of them are truly environment designers but rather illustrators for which environment design is just a secondary part of their work.
I strongly recommend you start by researching the jobs you might be interested in. Look for blogs or interviews from professional artists you admire or even ask them directly about their jobs. If you don't know where to start, I recommend Bobby Chiu's youtube channel which is full of interviews with successful professional artists. It's mostly american entertainment industry, though. I would have no idea where to start to learn about anime. And there are many other artistic jobs out there that you might be interested in.
Once you have a pretty precise idea of what a job is, ask yourself if you think it can satisfy you in the long run. Ask yourself if that's all you want to do with your career. All jobs have interesting or rewarding aspects and also tedious and tiring ones. Does the good make the bad worth it?
The only way to live without regrets is to make a fully conscious decision that whatever path you take is worth every penny and every second invested into it. Getting to the point where you can make such a decision takes time. It requires that you dig deep into the fundamental desires that you have, beyond the immediate things like fun, pleasure, money, fame, etc. It requires that you examine all your options carefully. It requires advice from people with more experience, that you trust and that have already made a similar choice.

I also feel like you're not pushing your analysis of style far enough. Either you're focusing too much on the "how" instead of the "why" of a choice (things like painterliness, cleanliness, round vs. slim, detail, realism are not things that are good by themselves but that have a purpose), or you're being too vague about what you like (things like "energy", "atmosphere", "gorgeousness", "pleasantness" are concepts that are too vague to work with). Let's take each of your points by itself.

ROUNDED VS SLIM

I feel like my style is super rounded and chubby, I really love styles that are more slim (look at : quillcoil). I feel like this is because I use circles as a base for my sketches.

CLEANLINESS AND PAINTERLINESS

I am a huge huge fan of certain artists in particular for backgrounds, but have had a hard time trying to achieve the same level of cleanliness they have in their art. e.g. yuristorm 
bluekomadori : I love the smooth cartoony yet painterly stuff this artist does! ... clean and pleasant

So this one surprises me a little. Your characters are already squeaky clean. So if I understand properly, you're just saying that you don't manage to achieve that in your backgrounds.
So why don't you manage to transfer the cleanliness of your characters to your backgrounds?
Once again we need to answer both the "how" and the "why".
The how should not be difficult for you, because it's the same as for your characters.
I've been thinking hard about it and I think that the problem is probably that you also want your backgrounds to look painterly, but you're misinterpreting what painterly means and more specifically you seem to think (at least instinctively, maybe not consciously) that painterly means you can allow yourself to be random and maybe even a little sloppy with your brushwork. 
So, yes painterly does mean visible brushwork. And yes, the fact that it makes things less artificial and more organic is part of what makes it appealing and that does come from a certain imperfection of the stroke and the texture. But successful painterly styles are actually based on extremely purposeful brushwork. There are too many brushstrokes in your backgrounds that don't describe anything and only create distracting colour contrast and pointless shapes. If we want something clean and painterly we can't have that. It would be a different story if you were going for something like impressionism, but cleanliness is then out of the question. 
If you want to achieve cleanliness, you cannot allow yourself to have nondescript, purposeless shapes and colour variations. Your brushstrokes have to correspond to something. The main idea is to start with simple shapes of flat colour and to then add very simple, very soft colour variation on top. Precise brushwork is paramount. Brush control can be practised with exercises  (here's a video on the subject, that focuses on pencil technique but a lot of it can be applied to any type of brush or stylus; use your elbow and not just your wrist and fingers; the exercises are the same). But more important than that is visualising your shapes before you put down your strokes. No use having perfect brush control if you don't have a good shapes to make. Visualising is a large topic that I don't want to go into here. It's somewhat intuitive for most people. If it isn't intuitive for you, the basic solution is simply to use construction lines and then detailed lineart for everything, just like you already do (I suppose) for your characters and even if you then discard the lineart once the shapes are blocked in. It's important to prioritize the shapes over the shading/colour variation. Then, the brushes and techniques you use will make the difference between squeaky clean like your characters and yuristorm's style or painterly clean like bluekomadori :
- squeaky clean: selections, 100% hard geometric brushes and maybe even vector tools for the block-in; and masks, selections, 0% hardness round brush, gradients for the colour variations
- painterly clean: just precise brushwork guided by visualisation of shapes/precise line sketching for the block-in; and pressure sensitive brushes, low opacity/flow brushes, "fuzzy" brushes, blending/mixing brushes for the soft colour variations

Then there's your first question:

First thing I would like to ask is if you think my more painterly style takes away from the most cartoony, clean lined look of the characters? I always wondered if this clashed, and if it does clash maybe what type of background style would be super successful for my artwork.

Painterly styles don't always clash with cartoony characters. Think classic Disney animation like the Lion King, for example
It certainly creates a contrast. It clearly separates the scenery from the characters. Is that a good thing? Depends on what you want.
If you want a strongly character- and story-driven piece, where the scenery is just here to support, then it's a great idea. But if the characters aren't important, if they're supposed to be part of the scenery, then it's a bad idea.
As a general rule, treating everything in the same style is a good way to create unity. But having certain parts treated differently can help them stand out and give your piece more of a sense of purpose, if that's what you want.
Think of it this way: if there is a meaningful reason to separate certain elements of your image, then it can be a good idea to treat them differently. But if those elements have no reason to be unique or to grab attention, then best use the same techniques and style all over.
It's also a matter of balance and taste. It's undeniable that you're creating a separation, but whether that separation is interesting or distracting isn't exact science.
Frankly, I don't find the separation distracting here at all, because it's not very strong. (I'd even argue that style consistency is much more of a problem in my own work than in yours.)
This is because:
- the line-art is not very noticeable in the characters
- you use similar colours for the characters and scenery
- the background is still very simple. Not quite as minimalist as the characters, but the strokes are still very blended and the extra visual activity from the visible strokes is balanced by the fact that the shapes of the background are simpler

MORE REALISTIC CATS

My style is quite cartoony, lacking the realistic element I really love from Magasushi’s work and would love to know how to develop my work into looking more like cats

If I'm interpreting correctly, what you're saying here is that you would like your characters to look more like real cats. I don't think it's a question of cartoony versus realistic. Yes, his work is less clean and tidy and somewhat more detailed, which makes it feel more realistic, but it is still very stylised and barely more realistic than yours. But I do agree that his characters are much more cat-like and yours are a little more vague and sometimes even feel more canine than feline (like the furthest character in the drawing that I'm [supposed to be] critiquing). You also don't need to get less cartoony for your characters to look more like cats. For example, I would argue that Disney's "Aristocats" are more cartoony and yet more cat-like than yours.
To me the problem is that you've developed a stylisation that's insufficiently based on observation of your subject: cats. It's back to our "4-step method to draw anything in your own style". To develop a successful stylisation, we have to break realism if and only if it helps us emphasize a certain quality of our subject.
You haven't spent enough time in step 2 - studying our subject, which here means studying cat anatomy, proportions and behaviour - and the result is that you are sometimes involuntarily breaking realism in ways that are just making your subject less recognizable instead of increasing some of their already existing qualities.
One thing to keep in mind is that we aren't studying anatomy, structure, behaviour in an absolute way, but in a comparative way, so as to find those "qualities" that we can exaggerate without breaking likeness. We're not concerned by exact measurements, but by what makes a cat recognisable and different from other animals and objects. This way we will be able to know what we can or cannot exaggerate.  
I can't help you much more than that because I don't know anything about cat anatomy or behaviour. But my intuition tells me that the snouts often feel too long and that fur "bangs" dangling in front of the eyes are not a thing that exist among cats. It's just a feeling.
Then we go on to steps 3 and 4 where we carefully exaggerate and leave out things in order to emphasize qualities.
If you're not comfortable with stylisation by careful emphasis, no worries. It's hard. It takes practise. In that case, what you want to do is try to understand how other artists have done it before you. I would strongly recommend studying the Aristocats for example. Once you have good knowledge of cat anatomy, ask yourself what parts of anatomy they are breaking and what parts they are keeping and exaggerating and how that helps them make a strong character design. For example: what are they exaggerating and keeping and leaving out to make Duchess look so elegant? what are they exaggerating to make the kittens so cute and feisty? etc... The character design in there is brilliant. Once you've figured out the answer, you should be able to apply these same ideas to your own drawings and then use them as a base for your own concepts.

BREATHTAKING, LIVELY, CROWDED ATMOSPHERES

For this piece I really wanted to create a crowded lively atmosphere, and know the piece probably would have better achieved this fact if I had added more characters into the scene.
I'm continuously enamoured by the subtle detail put into anime room pics e.g. sister by tomiokajiro. I love love LOVE all the things to look at in this piece, it probably took forever.
n-kim : I love the business. The amount of detail and atmosphere they bring to their full scene images just takes my breath away
bluekomadori : so much energy and things to look at

Well, this time I want to congratulate you. For once you're both getting the "why" of the success (the lively atmosphere) and part of the "how" (detail and business). However, I have a feeling that it's still a little messy in your head and we need to be more precise about the how.

Detail and business are not sufficient to make an image breathtaking or lively. 
If there isn't a strong sense of purpose, something that unifies all the business visually and/or psychologically, then it just becomes messy and disorienting and un-readable. To be completely honest, I personally find that there's too much detail and contrast in yuristorm's work and if I'm tired, it makes me dizzy just looking at it (then again I have a medical condition that explains that). It's also not just about excessive visual activity. If everything stands out then nothing does. If too much is going on, the image becomes about nothing and that's a sure way to lose our audience's interest which is the death of an artist. A picture with a lot of detail will often better catch your eye, but if nothing ties it together, then people will quickly lose interest. With the attention span of people on the internet that's sometimes sufficient to get a "fave" or a "like", but it won't get you very far; subtlety and depth aren't completely lost yet.

The art of tying a busy image together and controlling visual interest is a vast topic that I can't tackle here. If you want to learn more and have a little money to spend you can take N. Fowkes's pictorial composition class on schoolism.com. If you can tie tons of detail together, you'll have the gorgeousness that you desire.
Now onto the lively, energetic, atmospheric quality.
This is done by being very purposeful in what kind of detail we add in. The genius in a scene like the one above is that each detail has a reason to be there. It tells something about the characters, who they are and the life they have. Even though it's a single picture, it instantly makes it more lively and believable.
As a general rule, adding detail that makes sense is a great way to make an environment feel more life-like and believable.
But it's not any kind of detail. People don't just want "things to look at" they want interesting things to look at and they want it to make sense with the whole picture. For a lively mood to be achieved, that detail needs to serve the liveliness. We can use detail for other things. For example, in many epic fantasy scenes, detail is used to increase the sense of overwhelming scale, of tension and action. Not the same kind of energy at all. Here the detail gives a sense of casual and playful messiness. And BAM! we have liveliness.

In n-kim's work it's less about describing the characters through detail than describing the atmosphere of a place through detail. And the characters are actually part of those details: their expressions, actions, attitudes are all contributing to the feeling of mood.
Getting that much detail doesn't just happen. It's done by spending time developing your characters, you scene, your world and thinking what about what kind of detail you could add that would tell a bit more about your scene. How would the characters interact with the world and each other? For a scene to be believable, you need to observe reality like an artist (remember the exercise above?) and store all the real world details somewhere (in your mind or a sketchbook) so that you can use them later. Or you can just gather tons of reference and add as much as you can into your picture. Even better: do both the observing and the reference using. 

So back to your piece.
Frankly I'm not sure that your piece needs more characters. It would certainly make it more crowded but not necessarily more lively. I might be wrong but I think that liveliness is more interesting to you than crowdedness. At least, that's the idea I'm getting from the artists you've picked out as your inspiration. You can achieve visual crowdedness with just a handful of characters as we can see above and also in all of yuristorm's gallery.
To me the thing that's most missing for the scene to feel lively is expressive characters caught in fun and natural attitudes and actions. The facial expressions feel very bland to me. The two front ones seem to be playing around and somehow managing not to be smiling at all? That does not make sense to me. The direction of gazes is extremely important. Our brain instinctively tries to follow it and make sense of it. The top character is looking sideways at the viewer which is awkward and stiff and 4th-wall breaking. The black cat is looking intently at the water but it seems weird to the viewer because we can't see anything in the water and it takes some time before one makes the link with the fish the others have caught and understands that he's waiting for a fish to come within grasp. I realize that you probably don't know how to make the water look transparent and have fish in it, but I'm saying that such an intense directional pose and gaze needs to visually lead to something interesting for the viewer to be convinced. The rightmost character is looking out of frame without us having any hint as to what is over there, which is unfortunate in a scene where you don't want to create mystery or dreaminess. The solution to all this is to dig a little into what your characters are doing. Don't just draw a character, try to find something interesting for them to do. Something that speaks to the liveliness of the scene. Think about what emotions and intentions and thoughts the characters are having. How can you translate that into their pose and expressions. They're fishing and playing. That's a great start. But how? How would their different personalities translate into that situation and how can you show that in a way that makes instant sense to the audience? 

You also want to try to capture natural poses and movement. This is what artists call the gesture of a pose. I don't really have the time to go into detail. You can look up "gesture drawing" and you'll find tons of stuff. It is, of course, practised by drawing from reference, especially from live and moving models.
I do agree that we need more meaningful detail for it to feel crowded or busy. That detail doesn't have to be characters however. I think that the background also needs detail. It feels very nondescript. Here's a couple questions:
What kind of vegetation would grow here? (you can look more closely at yuristorm who achieves a great amount of business just from vegetation)
Is there no other wildlife than the cats? Terrified fish jumping out of the water would make a great addition.
As sentient cats with clans, there might be signs of them living here, some form of evidence of civilisation. "Aftermaths" of past events (think of all the trash and untidiness in the bedroom of the above picture and how it hints at what they do and how they live) What would those be?


As to the "it must have taken forever to draw", sorry if I'm bursting a bubble but backgrounds in manga often use pre-rendered 3D assets which they simply import into their drawings. No drawing required, simply adjusting the colour and the lighting. I'm pretty sure it's the case here. There's a few telling signs, like suspiciously perfect and detailed lineart that doesn't fit with the lineart of the characters as though they had spent more time on the props then the actual characters, objects that have perfect perspective by themselves but whose perspective doesn't fit with that of the global scene, absence of occlusion and cast shadows, objects that look suspiciously like known brands even though they are obviously not a sponsor of the artist. Here I'm 90% sure that that's how these things were drawn: the computers (especially the keyboards), the speakers, the can of 7up, the biscuit box, the remote control the entire content of the shelves, the books on the bed, the xbox controlers. I'm also not ruling out the fan and the earphones. It can also happen that the entire background is a rendering of a 3D model on top of which the artist will draw his scene and characters. Here I doubt it's the case because there are too many perspective mistakes, and credit has to be given to the person who did the 3D models of all the props, but it's highly unlikely that it's the same person that drew the characters. People who have what it takes to compose this kind of scene with characters in a complex pose, great lighting and a superb sense of story don't usually like to spend their time on accurate reproductions of remote controls or shoeboxes.

WATER

As well as this, I was especially trying to work on the reflective property of the water on the characters fur. Experimentally, I added the blue lines round the brown character and i feel like this really turned out nicely!

I don't really agree with you. Though I do think it's has an interesting aesthetic to it, I don't feel like the blue lines look like reflective water at all. To me it's more like a super saturated rim light (a term that comes from photography lighting, no time to explain more) which is a great trick that makes your characters pop and strengthens silhouettes.
It feels like we have another case of you stylising things without studying well enough how your subject works.
I feel like you've decided to try to represent reflective water on fur from what your intuition tells you, in a symbolic way, instead of first learning how reflection works, how to reproduce that in your drawings, and then eventually how to stylize it by emphasizing something interesting (once again the 4-step method to learn to draw anything).
I'm not going to explain how to paint reflective and transparent materials like water here. First because you can find that elsewhere. Second because it would take too long (no it's not easy). Third because before you can learn that properly you need to learn how to properly render light hitting opaque, non-reflective objects, which you clearly don't master yet.
One thing I can tell you, however, is that water doesn't get that blue unless it's deep and pure. Here it's a super thin coat on fur, it's going to be transparent and have white highlights. 
But now that I come to think of it, wet fur isn't even particularly reflective, the most striking thing about it is how it clumps up into droopy points:

As you can see here, not even close to a bright blue highlight.

DEPTH AND PERSPECTIVE

Finally, I would like to know how to improve my water-drawing skills. I feel like the water in this piece does not have much depth, and have struggled with drawing/painting water in a way I'm happy with.

So as I said, I'm not going to explain how to draw water here. I think you have more fundamental skills to work on and I don't want to crowd this critique too. However I do want to talk about the problem of depth which you have here and also in all your other environments.
There are a number of ways of creating depth in a painting. You can watch the three videos on the illusion of depth in the Drawing Basics category of this page to make sure you're up to date.
I'm not quite sure how many of these you already know.
But the main problem you have is that your brushstrokes are breaking perspective.
The basics of perspective is that things get smaller the further away they get, but you don't apply that to the thickness of your brushstrokes, who mostly stay the same size everywhere in your environments. Here you even used thinner brushstrokes for the water that is closest, which is actually inverting perspective and making the water completely flat. In contrast, the furthest hill on the right does feel far away because you've put in small detail with low contrast.
Of course you do want more detail in the foreground than in the background, but strokes that read as being the same thing should get smaller and have less contrast as they go away.
For example, these strokes (the parts that aren't highlighted in red) have the same colour, the same thickness, the same hardness of edge, so they read as being the same thing, but they're clearly not at the same distance from the view point so the furthest should get smaller and have less contrast with the surroundings but instead it has the same size and actually has more contrast. Perspective is broken and it looks flat.

SO. WHAT NOW?

It's pretty clear to me that you're a talented individual with a great artistic intuition. 
I hope my rant on style hasn't bored you to death and that you've found some interesting thoughts in there on how to shape your own artistic path in an ambitious but reasonable way.
I also hope that I've answered your questions properly. I'm going to be honest. I'm not entirely satisfied with this critique and despite the fact that it's stupidly long, I would still want to explain certain things better and also talk about a bunch of other things. 
My opinion is that your next step is to get studying seriously. Doing studies means stepping out of your comfort zone in an attempt to learn new tools and not doing countless drawings hoping that improvement will happen. 
I fully support you continuing to do your drawings from reference like you've started. But what I suggest is that before you start one, you first think about what you want to learn by doing that drawing. This means you need to choose reference (photos or from another artist, btw) not just because they are pretty but because you think "I want to learn to draw that" or even better "I want to be able to achieve this thing in my own drawings". Don't pick too many things to learn or practise at once. And instead of trying to make the prettiest drawing, you will judge the success of your drawing by how much you've learned. You can even stop midway if you already feel like you've learned something. Then, in your own original drawings, you can try to check just how much you've learned by trying to incorporate this new knowledge.
If you find that you are not really learning anything from these studies, then it's a sign that you don't yet have the knowledge to properly analyse your reference and that you need to go find it in a class/book/tutorial/video.
Doing studies cannot go without good observational drawing skills (this is step 1 of the 4-step method to learn to draw anything in your own style). Your referenced work shows that you already have some good grasp of how it all works. But certain choices you make (like how you tried to paint water here) suggest that you haven't quite mastered visual analysis of your reference yet.
I suggest starting by watching all the Drawing Basics videos on this page and you can also read my previous critique where I go into more detail about some of the most fundamental aspects. Some of this will not be news to you, but I think it should help clarify your ideas. The only thing that is missing from Proko's videos is proper theory of how light and colour interact. There are probably some good free tutorials out there but I haven't found them yet. I can however recommend the Fundamentals of Light and Colour and Fundamentals of Realism classes from schoolism.com if you have the money.

In parallel, I recommend training your artistic eye everywhere you go in the way I described at the beginning:

Seeing like an artist exercise

1. Why is this interesting?
   
2. How would I go about communicating this?
   
3. What would I do to make it more interesting?
   

    Bonus points if you actually sketch out your ideas to check how good they are.

In a couple of years you will probably have to decide whether you want to train to become a professional artist or pursue another career. If you want to go to art school, you will probably have to create a portfolio first. You may also decide not to go to art school and to train yourself online. Those are three extremely interesting topics that I'd love to talk about, but I don't have time and I'll have to be content with pointing them out to you and telling you to think hard about them.

• Parting words