Part of my process, after many, many layers of collage (from
paints to paper to cardboard to found objects) is to paint over everything I just did with a white gesso. This helps me not only get ready to start from "the beginning", but also to not be precious about anything I created before that, as I know everything below that layer holds its own history.
This video gives you an idea of what I am working on now. I'm preparing for a new collection by either creating many layered collages, or painting over old pieces to start fresh.