Collages are a way to tap into what Jennifer Crusie refers to as "the girls in the basement." I first began collaging after attending a workshop given by RITA® Award winner, Barbara Samuel.
For me, the visualization of my characters, and their journeys, is the most valuable tool in the box. As soon as I begin working out the characterization, plot, setting, etc. in my subconscious, I start building my collage. Sometimes I start with an 8-1/2 x 11 piece of light cardboard and then add that to a larger poster board. Sometimes, I'll see something I didn't realize before, just staring at the final work.
Use lots of Mod Podge® all-in-one glue, sealer and finish, sealing the whole mess as you go. Begin collecting visual images which speak to you, clipped out of magazines, or downloaded from the web. You can also attach other items such as glitter, beads, fabrics, etc. There are no rules—let your subconscious show you the way.
Below are examples of collages inspired by completed and in-progress works.