Because I keep getting asked this and my art is majorly sucking today anyway. Have a shading tutorial.
I learned this method from other artists, so it is NOT something I made up, but I can't find some of the old tutorials I learned from.
If you really want to know how to draw/color/shade/etc. for formal training purposes (in other words, you want a job in art at some point), go and learn from a professional, not me. ;3
Also, have a River, he's adorable! :3 He's owned by

. ^^
(and your art is so amazing