When I begin a collage I often start with an idea generated by a particular image. Using the constraint of working with found images I build the picture, trying out many combinations and arrangements until the final composition emerges - often quite different from my original mental image.
I find collage a very liberating medium. Without all of the various assorted images to play with, to arrange and rearrange, I would never think of the stories which emerge as I work. It's a very time-consuming process. Sometimes I am too devoted to an idea - the picture as preconceived in advance - and it is a struggle to resolve the composition. When a collage is successful, disparate cut-outs, paint, and idea come together as a seamless whole.