Every image I do is done in four passes. Stage 1-rough pencils, stage 2-flash cleanup, stage 3-color tweaking, and finally stage 4-texturing in photoshop.
Suprisingly enough...the stage that takes the longest for me is color. I could spend hours just doing variations. It's both a fun and fustrating at the same time. It probably stems from the fact that I dont really know what the hell I'm doing.
So in an attempt save time and keep my sanity, I've tried doing to do quick 2-3 minute color thumbnails. Here's an example from of a layout I was recently working on. Special thanks to Mr.Sean Scott for the permission to post ;)