Starting January 1st of the New Year, I have been doing a daily 15 minute warm-up of collage before I start working on other paintings. I was given a sketchbook with fairly heavy weight paper for Christmas and I drew 2 rectangles on each page.
Over the years I have saved and collected various papers that could be used for collage so I have a lot of textures and colors to choose from. I tear or cut out shapes and glue them into the rectangles. It's a fun and easy way for me to play with different color palettes and compositions without worrying about the outcome. If I get some I really like, I may try to make them into a bigger painting later!