So I picked up an toned sketch book the other day, and a white charcoal pencil of course (I actually bought 3 different ones to test them, and Faber-Castell makes my favorite one.) For quick sketches I really like the medium, it allows me to see my initial idea the fastest because not only can I push back the forms of the drawing with the black pen, now with the white pencil I have the ability to to the form forward. Now I can just attack a drawing or idea while holding on to that original inspiration for longer, and I really think thats a good practice to get into.