I'm starting out drawing now; and have got traditional sketching and lining down pat. (Digital) Coloring's where I'm having some trouble. Not gonna try coloring by hand, cuz if I make a mistake... Well; yeah. Impossible to undo. SO I'll be doing coloring digitally. Best image programs I have access to at the moment are GIMP; and a free Russian version of Adobe Photoshop. The latter's a pain to work with cuz I don't speak Russian. Anyways, back to the topic. Does anyone have some good pointers for shading/shadows/etc; and suggestions for better art programs?

...Hell; any art tips in general'd be much appreciated.

And before you ask; NO. I don't have a tablet, much less one with Paint Tool SAI. Will be getting one as soon as I can though. Current traditional sketch & line --> scan --> digital color is just temporary.