Every now and then I host a painting day with some friends, inviting them to explore and experiment. Recently we got together and went back through some basics in creating light and shadow as well as some color and composition studies.
We started with some "warm-up" paintings which in theory are supposed to be quick and expressive exercises to get you loose and feeling free with the paint. For us though, we were focused on having something we would want to keep when we were done and our "warm-up" exercise lasted a little over an hour.
After a while we moved on to slightly larger paintings with more abstract expression and intense color palettes.