I have a bit of a problem with keeping my hands steady, too.
A couple of things that help me when I need the steadiness...
1: Take a few really deep breaths and try to make sure I\'m relaxed before I start.
2: Hold the mini in your off hand, and press the heels of your hands together, so that, if there is any trembling, they (both your hands) are doing it at the same time, in synch, so that the painting doesn\'t reflect it nearly as much.
For additional relaxation, some might also suggest having a pint before you begin...