Help with shading?

[Fedx]

So, this have been a problem of mine since... well ever haha, I made a drawing, scanned it, traced it in photoshop, and added color and shading in GraphicsGale. This is the image in question: I want to know how to improve the shading in it, while keeping the black outline and not overcolor it. Thanks!

[abstauber]

I think you will right on track once you get the light-source right.

Please take a look at this and post a new sprite with a global light source.
http://www.natomic.com/hosted/marks/mpat/shading.html