Excuse my mess, I get lazy with tutorials XD My hand writing is also blehhh but I hope you can read it!
Something rather simple to explain shading. Sorry if it's a little vague, a lot of shading goes with whatever is in the drawing, so it's just basic shadow or lighting. Shading anything requires a unique technique that I challenge you to find through trial and error with shading. That's how my style came about.
Anyway, this walks your through how I did Ryu. It's not very complex. It was done in roughly 1 or 2 hours. The style of cell shading is one layer cell shading (mine is usually 2-3 layers, but I'll make a more detailed tutorial for those methods).
Hope this is helpful!
Art (C) AgentWhiteHawk