Before I even got my idea, I prepared my surface - in this case, a 4 x 4 sheet of plywood nailed to a back frame of 1 x 1 wood strips. Then coat the surface with primer. Once I get my idea, draw it up on the computer, print it out, then scale it up onto the board. Then start having fun with paint - in this case, good ole latex interior matte house paint - sample sizes.