I used mainly 2 brushes for this (as well as for most of my other photoshop stuff)
Both are custom brushes I made myself.
One is a dirtbrush, which I used for the background, and the actual painting was done with a squarebrush. I find that square brushes give nicer texture than round ones. At least the way I work. I found that it is best to experiment and find a workflow you are comfortable with and get into photoshop, before even trying to copy other people. Once you know the program better you will be able to look at paintings and in many cases just go like "Oh, I see what he did there"