I love to collage. I find it very relaxing.
When I create a collage I use scrape booking paper, stationary, and magazines. Once I cut everything out I loosely arrange it to get an idea how the finished art will look.
I use matte medium to glue the papers to the surface. You can also use all purpose glue, watered down slightly. Stamping can be added in a few places to give interest to the piece.