Although I can't add much to this post (almost everything I'd want to say has been said well already!), I can offer general purpose advice to the community in the form of two ways to practice texturing in Pixel Art so that you can get better in a hurry with texture (as long as you are already familiar with pixel art and practice this stuff of course!)
I've offered two examples of practice in this image -- the first, of course, is learning to animate texture, such as fur or grass, by rotating it or disturbing it somehow using wind or other such means, and the second is learning texture by dramatically altering the light source while retaining the form/silhouette of the subject. You will need both to effectively animate naturally dynamic substances such as fur/water/etc.Be warned
-- Both of the following methods are pretty advanced pixel art techniques, so if you're not familiar with pixels as a medium to describe form in general, you're likely to have a lot of trouble using these as effective practice. You need to understand first how to render forms in pixel art via silhouette and use color/light to indicate depth and form to begin with. After which, you should be skilled enough using these methods to practice texturing.Practice method 1: Texture Disturbance (Wind/Rotation/Shimmering)
The goal here (at least for the long hair) is to maintain the silhouette of the clumps as much as possible while offering accurate cast shadows across the form by keeping in mind foreshortening of clumps facing the viewer that are otherwise invisible. You will need to maintain a sense of the position in space of each foreshortened clump (independent of the pixels!) and convert that as best as you can into the pixels and resolution you have available. In a lot of ways, this is like doing a complex 3D shape transformation in your head, but instead of the computer doing it, you are doing it intuitively and then trying to fit the resulting 2D shape on the screen into a sort of LEGO pattern (using nice clusters wherever possible!) If this first method seems hard and/or time-consuming to learn -- it is -- but it is also possible
, as I and many others have accomplished it (with a LOT of practice in most cases of course!), and we're no more special than you are. It's just practice at getting a sense of where the FORM is in space AFTER it has moved, and then translating that to nice looking pixel clumps in a nice-looking silhouette, all of which there is NO science behind, although basic art principles will help a ton here if you have them at your disposal.
Short hair or tiny substance disturbances (see the side of the big fox's stomach area) are a lot more simple to describe, as you generally tend to need only to alternate the dither grid pattern from dark/light/dark to light/dark/light and vice versa. In cases where there are minimal disturbances, you may only need to shift a single pixel or two of the dither pattern in far away areas to indicate a very light wind. Heavier wind requires more pixels to be altered, but the pattern alteration remains the same.Practice method 2: Dramatic Light-Source Change
The second method is pretty self-explanatory -- you simply change the light source dramatically from what it was originally. If it's from the front-left, you make it directly overhead. If it's from directly overhead, you make it from the back and on the right. In the example image, I did this with the small fox. The original fox's light source was from the front-left, so I made it directly overhead as best as I could in order to still maintain the baby fox's form. This is when it's very important to have a strong 3D understanding of your subject, and this starts in the silhouette stages. What I basically did was reduce the baby fox to a flat shade (next-to-darkest orange) and redid the lighting from that point onward.
In regards to texture, once again, you must maintain a sense of any major three-dimensional protrusions across the form, so it's important to know where these occur from silhouette and beyond so that you can light them accordingly. In the case of the face, I altered it a little to have a more plane-like structure around the cheeks so I could indicate a hint of some fur there with the lighting. Places like these are very important to have to indicate form better since they offer an opportunity to cast shadows across the rest of the form which adds a greater sense of depth to the image. Practice this and not only will your sense of depth become more honed, your sprites (and drawings) will look a lot better too.In Closing, and for any Beginners reading this:
Texture is generally technical in nature, as far as the creation process goes, so it's not very difficult to achieve in most mediums where you have more room to describe it -- although, at the same time, that also means you have to know exactly what it is you're describing. Those techniques I mentioned above help you cheat this a little, as pixel-art gives you very little room to describe specific materials and textures, since you generally only deal with shiny/dull/rough/bumpy/jagged materials/textures at most. That being said, you still need to know how they work, especially in motion. Even the thinness of a spider-web vs. the thickness of rope is possible to describe in pixel art, but these sorts of things can only be suggested if you know how both they and the pixels work together, although I'll save that explanation for another time.
In short, nothing can beat a full visceral understanding (if possible, not just reference images!) of your subject/reference when it comes to describing it in any medium -- especially when using more accurate mediums like good ol' pencil and paper. Pixels can only take you so far in how much you understand a subject (due to its limited resolution). Though despite this obvious fact, I see a LOT of new artists trying to learn art by learning pixel-art so they can escape having to learn to draw first (which is not necessarily WRONG, but it is very backwards and will take you [yes, YOU.] a LOT longer to get mastery over technical art skills in general if you go this route!)
Art, in general, as far as technical skills go, is, in a nutshell, learning how to describe form in order to achieve a certain impact on the observer.
Learning form (of which texture is also a part) through any medium (such as pixel-art) first rather than through intense analytic drawing studies of subjects (a lot more common nowadays with everyone wanting to learn to make games) is not something I would recommend.
Assuming you're learning art for the first time while doing pixel art, and you're just going to continue working to understand your subjects through pixel-art first, if I could offer any medium to do this in first, I'd actually recommend 3D sculpting. I suggest this for one reason only: you can't skimp on form at all, and it'll really show you just how much work you really need to put into your subject knowledge before you can render anything at all convincingly enough in 2D since forms can become very complex VERY quickly -- especially when you add lighting and materials, and in this case, texture -- and it ALL has to be done manually
If you're serious about pixel-art, whether you ever intend to animate pixels or not, getting to the point where you understand how to render textures and materials to the point where you can animate them (convincingly!) is a place you should strive to reach, but if you're just beginning pixel art, don't worry if it's difficult -- as I said before, this is an advanced technique. You ought to first learn how to fully render basic 3d forms -- then, and ONLY then, should you begin to worry about texture, materials, and animation.
Remember though -- this is still art! So, no matter your skill level -- just have fun! Everything, even hard-won skill, comes in time!