hehe, I actually use a pencil a lot (I just don't post any, I try to make digital coloring for that, but they really are time consumming). I have so many sketch books, mostly to practice (some drawing are really good...others, well not so much :-D). Lately I am doing more pencil drawing, getting those more living motion strokes and getting to notice more the little details that makes them look more alive (just like your drawings, they have the "je ne sais quoi" touch to them)