i like this, lol i wanted there to be some ponies on leashes when i do my comic but have them enjoy it rather than it be like symbolic or metaphorical as to having anthropomorphic horses being dissatified with being treated like animals rather than as intelligent as humans lol those are just my thoughts on your work
In Photoshop I use a brush tip called "chalk" its kind of a rectangle shape. In CS5... in the brush settings window, look at the default brushes. It is the middle one in the fifth row down I adjust it so... Size, Opacity, and Flow are all controlled by Pen Pressure. I hope I helped you!