I wanted to post a bit of the process that goes into one of these drawings. First, I usually pick a drawing that I did in figure class - like this one. If I don't have time to add color (which is usually the case) I'll at least make a note as to where the heavier shading is with a series of small "X's."
Then I'll take this drawing into a program other than Photoshop for inking. I find Photoshop's brushes to be a little limited for inking. Here's the ink (vector).
Finally, I'll bring it back into Photoshop, build up some layers, and break out the crayons. The whole process takes about 2-4 hours depending on my work load for that day. Here's the finished drawing with color. I've got a few more drawings from last night's class that I will be posting shortly.