Shading question.

[thernz]

Well, I mean you really need to work on your anatomy, but when shading, think of a lightsource. Shadows will be on the opposite direction of this "lightsource." But! You can't just shade it like HGDSFFG.

HGDSFFG
Instead you have to take in account the "3D" forms you're trying to represent. What parts are receding into space? What parts are beneath something else so light is being blocked out by it, cast under shadows or whatever? After then block in a darker color for where you think the shadows might lie.
This isn't a pixel art color tutorial but I feel it's crucial to read when coloring anything. You can at least understand how the shading is supposed to be like.
http://itchstudios.com/psg/art_tut.htm
It also details other aspects you'll need for coloring like highlights and stuff. I think you should reflect upon what it says and think of the best way yourself to apply these in a low color pixel format. Because manning up for yourself is more than half the journey.