I got a set of Derwent Inktense pencils and I'm having fun trying them out. They get applied to a surface just like any other colored pencil. But when you touch the markings with water, it changes to a vivid ink and becomes permanent.
I started with an apron I had gotten as a freebie from somewhere. I tangled with a Sakura IDentipen first. Then I added my colors. Frequently I used two or three colors at a time to get deeper shadings. Finally I added water (carefully ) with a fine tipped brush.
I plan to keep going, trying out more color combinations as I go. It's fun!