What I usually use are a combination of Airbrush and Water tool . If I want rough stuff, I'll go for marker tool.
Alright, here's a more detailed shot on what I use for my brushes. I still had a lot of people asking me what settings i use for my stuff I will be putting this on my FAQ xD~! well, plus i'm using the marker brush a lot more now, so here are my settings : ). If you have any more questions, feel free to note me xD;, but i feel like i pretty much covered it all here .