I'm using a method I read on TMP (I think), painting from the bottom up rather than the inside out. It works well for me when I do it right, because I'm less worried about staying "between the lines" as I paint. I just have to worry about one line, the other side will be cleaned up when I move up the figure.
The earlier martian test was painted top-down. I didn't like that as much, because it turns out often will rest the figure on its head so I can get to the bottom of weapons and equipment. This scuffed the paint off the already painted helmet. Bottom up works much better.
Also, I really hate painting white.