I tend to work mainly with just one brush, and its nothing too special...
Its one of the standard "Chalk" brushes. I played with the "spacing" options a little bit to create a little more texture and also set the "opacity jitter" to "pen pressure". Ive been painting most of them that way.
However, theres also a hand painted acrylic wash texture that was scanned in and used throughout. That accounts for the diagonal "sketchy" type strokes that you see in the image.
Ive been playing around with similar looks lately.
I'm sure that I'll move on soon and try to find some different things to do...
Thanks again guys!