Just some progress shots of this project, completed version here.
The earliest shot I have, outlined in Sharpie
The flat color is so nice here I almost wish I had stopped, or at least scanned it high res so I could continue in another direction from this point
Adding shadow and dimension, starting the highlights
More or less the finished piece. After the shadow and highlight pass, I decided to go back in with some complementary color and really try to push the depth.