I've almost done the same in this one but it isn't quite so obvious. I had great fun scribbling the colour on with water soluble crayons and then activating it with water. Where it became too dark I could blot it away with a dab of kitchen roll. I added definition here and there with various pencils, and drawing pens.
I treated this page in the same rather random way and feel that I am not really in control of what happens on the page. I just go along with it, hoping for the best! In fairness to myself, these pages look better in reality than they do here and at least I have learned what doesn't work and have enjoyed doing these exercises.