Noise and texture
Once these flat, poster-like colours are working, I can move on to the noise, texture and detail part of the painting. It needs to look believable at this point. If it doesn’t, keep adjusting until the forms make sense and are working with the surrounding colours.
Solving a jigsaw
Now I look for subtlety and variation in those flat tones. I average the areas to ensure that the entire image has the right value relationships, then look for the variation within individual pieces. It’s a little bit like trying to see the finished jigsaw puzzle image with just six key pieces in place.