Creating monotypes is an exciting way to explore image development. In art school, my focus was painting and printmaking - and doing Monotype work encompasses both and combines them together.
While I do have to start with "something," often it begins with selecting the paper or other surface, having a sense of the materials I want to use to start the piece, and then developing a relationship with the surface and the work specifically. A theme or concept is often not the place I start. Frequently its part of the process and evolves as it goes along and as I see the transformations that take place as the work progresses.
As with my methods of working in other media, it's an emerging process. I like to think of the processes of Montotypes and even Mixed Media as generational. For example, typically a Monotype will begin with an original, physical print of some sort and develop from there, including physical media like pastels, colored pencil and more - and even occasionally digital inclusion.
Here's a very short, silent, video showing the making of a monotype print.