Sometimes I'm lucky enough that ideas come at the moment when I'm ready for them. So I grab my pen and sketchbook and draw them out. Sometimes I may jot down some notes on composition and color choices. What seems to happen often is that when I'm cooking or someone else in my house is cooking, things come together to form the perfect painting. Both sketches above and below were done as Mikey cooked some burgers one night.
Other times I think about how I can change a subject that's already been dealt with. Like the first sketch below, a different composition of the Three Peaches I painted not so long ago.
There are times when I grab a camera instead and take multiple shots of groupings of objects. I have a collection of both prints and digital images of future painted still lifes. But nothing beats the creative feeling of drawing them, whether from observation of imagination. The feeling of the pen running through the paper is unparalleled. If I could just now find the time to execute all these ideas!