Dribble--the main course.
Initial sketch was done in Sketchbook Pro, a tool I sometimes favour to Photoshop for initial sketches. Used the "symmetry tool" since this was going to be a vector and I wanted a very clean mirror image.
I like to block in the main colors in Illustrator, using a mid-range tone that I can either take to the darker or lighter side in photoshop.
Final coloured design.