I was really bothered by my inaccuracy while drawing on my desktop vs drawing traditionally for a really long while, then I discovered that I didn't map my tablet correctly... hemorrhages
I then attempted a quick (is an hour considered quick?) portrait drawing on CSP with a nifty side pencil I downloaded somewhere. There's quite a learning curve with shading evenly. All in all paper is still the best medium for these things, but there's a sense of satisfaction with being able to do it on my desktop too.
Here's the reference.