Just like any other activity, it's a good idea to keep your painting muscles in good shape...otherwise they might just get flabby. I like to think of this sort of exercise as painting without an agenda. Find whatever surface is laying around the house and start to drop layers onto it. Mix mediums with different types of paints, pastels, solid colours, typography, line work, texture, collage, spray paint...anything you can get your hands on. The more the merrier. The best part is that there is no finish point. Simply stop when you feel the painting is interesting, or store it away to add to again later. Often as in my recent example, crops of the final painting can hold quite a bit of curious details within them.