Just some artwork I created [Art]

[Gors]

well, first of all, interesting stuff you got there

Though as you already know, there are a lot of places you could be better on, such as lines and stuff. I'll get the pic that stands out the most for me,



which has everything you should work on (and therefore applies to all your other words listed in the post). I'll treat every issue in topics:

1-Color. Perhaps your worst problem in all your stuff. The colors are dull, really boring and really pale-looking, and you can't really sense depth with the shading you've applied to it. Coloring isn't about picking a color and gradually increasing brightness/darkness to shade. There's a lot of cool things you can achieve with colors. A quick research on google brings me up this example:



See how the shading is achieved not by simple color darkening, like you did. The artist has a very dynamic choice of colors: notice how the woman face goes from a yellow tint to a blue shadow, and how defined the lights/shadows are. This difference of light/dark is called contrast, and it helps hus perceive volume in a flat, 2D screen.
Dealing with colors is quite difficult as there are no fixed rules for the colors you pick (nothing in art does), but experiment. See color theory for more pointers.

2-Texturing. When you shade or color things, you must consider the texture of the object you are trying to portray. In this case, flesh or skin shading is quite homogeneous, but fabrics, fur and any other surface has its own texture, which you must portray.



This is how wool looks like. Notice its texture, and its coloring (it's not exactly white, it's a dirty white that becomes 'brown' when shaded). Pick references when painting or drawing textures, and you're good to go.

3-Volume. This is also related to the first three. When drawing, you need to imagine the thing you are drawing in 3D. How would it look like? How will the lights interact with it? Since your drawing has virtually no contrast, no volume can be perceived. It looks like it's all in the same plane, and therefore it looks really flat. The only thing that I can really see the shading are the tentacles behind the character, but even then they aren't great either. The way you shaded them makes them look like beveled surfaces, instead of a cylindrical tentacle with a pointy top, if you know what I mean.
It's important to 'view' the character in 3D while sketching, as this will be the starting base for all your work. If you fail to do so, the whole piece will end up looking flat (as is the case with this one).

4-Anatomy. This is also something really hard to master, but if you stick to it, you'll be able to do prettier stuff. There are a lot of proportion tips you can discover by analyzing the human body.



This is pretty common, you can find variations of this easily in google. Notice the muscle groups, their formations, and sizes. The arms' length end near the thigh; the legs are longer than the upper portion of the body; the foot is as long as the forearm; thighs/calves and arms/forearms have the same length. The more you analyze and study it, the more familiar it gets, so even if this looks hard, you have no choice other than try it.

There are many anatomy tutorials scattered over the internet so don't be lazy or shy and look them. They are pretty nice and having a solid knowledge in anatomy will give you a better result even in more cartoony styles, as they also follow the basic principles.

5-Posing. Also a part of the anatomy, posing is how you want to place the body in a situation. It's an important part of characterization so don't think on it AFTER sketching. It's one of the very first things you gotta think on.
If you aren't sure of the pose, try doing the same pose yourself. Use your body. If you feel that the pose is uncomfortable, you may want to change the pose.
Also keep an eye on balancing. Some of the characters you drew look like they're going to fall. A good way to notice this is to flip the pic horizontally. It helps a lot when trying to make a balanced pose.

6-Style. This one is subjective, but try a lot of different styles. Realistic, cartoon, anime, anything. The more you practice, the better. Don't just draw anime just because you like it. Art is about mastering everything, not just one thing (that would be boring as hell). Don't be afraid to experiment, try different media, coloring, characters or even landscapes. Anything goes.

I'll end here for now. Drawing is not easy, but if you work on it regularly, you'll get better at it.