Here is the way one painting, Fire in the Snow, part of the Egypt series, evolved.
if you start with a color's complement, the top layer will be more vibrant. I know the sky is going to end up in the pink-ish range, so I start with green-ish
I spent a month just painting the feathers on this one bird. Then I decided he or she needed a different face.
I didn't photograph every single stage, but enough of them so you get the idea. I worked on this painting over the course of about five months.