Thought I would share with you some of the techniques I have been exploring. I have been playing with water colour paper and using gesso to cover the paper. Use an old store card to spread it. While it is wet press some stencils into the gesso. I also used cotton reels, mesh, scribbled with an old pen outer, scrunched up glad wrap and anything you think makes a mark. When it is dry, you can use a wash of colour in a light buff or similar. When it is nearly dry use another colour and on a scrap piece of paper and swipe random strips of paint and scribble or put in some finger marks and place onto your background and remove. Continue until there is no paint left. Repeat. You can use the mesh again to make marks with paint.
I also use water solvable crayons to highlight the marks made previously. Scrape off any areas with your card or damp cloth. This will work well on canvas also. I continue then with college and use inks to enhance areas for shadow.