I thought it would be a good idea to integrate the warm/cool concepts into the familiar layer approach to planning a painting. The goal is to make awareness of color temperature an instinctive part of your thinking.
When you are making a picture that involves definite warm and cool statements, you may have to commit to the color temperature right away.
Most of the major shapes in this image need to be warm or cool right from layer number one. This does not mean, however, that you would be obliged to duplicate these relationships exactly. You're in charge of all the decisions. Knowing where you would like to depart from accuracy applies to color temperature, too.
Look at the three shapes in the central strip, for example. The middle shape could stand to be a bit more separate from the one on the right, so we could read the space more easily. Imagine the picture if that shape were a bit cooler than the right hand shape, while still warmer than the one on the left.
Consider the value spread between the left and right shapes. Could you see darkening the central form a bit? Or lightening it?
How about that shadow on the right? What would you want to do with that, in terms of color and/or value?
At what stage of the painting would you make your changes?
Look for an image (or use one of these) that invites a warm and cool treatment. Plan some changes that make the picture more to your liking. These could just be to make it easier, or they could be simply experimental. Write down where in the sequence of layers you plan to make the changes.