
“Okay, so I didn’t exactly know what to paint from the outset, so the first thing I usually do to get rid of the white canvas is to start doodling, just to spawn some ideas. I started by filling the canvas with a mid-grey value so that I could paint both brighter/darker values and push the image contrast in both directions.”
http://www.3dtotal.com/team/Tutorials_3/makingof_discovery/discovery_01.php