You could try starting with small brushes for painting/smearing and then go to even smaller brushes. And in the end use incredibly small brushes, like 1 point. And lowering the opacity to. I did do that with the mouse, in the old days. Before the war. Those $ 2000 tablets are terrific. They come with built-in LCD tv, DVD and some living miniaturized zoo elephants, encrusted in diamonds, don't they? If you just want to draw things with a pen, you can find tablets under $ 100. Doing paint and/or postwork with a mouse, is like kissing your lover with your foot. It just doesn't feel right... :-)