A coloring in photoshop experiment - Shoes!

I try to stretch myself, and get out of my illustration ruts -- i look for methods others use to give myself new ideas for how to do things. The below is an experiment in coloring in photoshop, this time using Channels. I used a pretty unfinished sketch to start with, but i kinda like the result. I used this tutorial as a base. Does anyone else have any good tutorials they've found useful, or other good tips?
fyi - here's the original pencil sketch



Feedback is welcome, of course!
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