Kyle Webster had a couple of demo videos I watched.
Something I learned that i plan to use a lot, whatever brush you are using, you can set it to clear. So you have an eraser that behaves just like the brush you've using. Great for texture building. The pick out twigs behind the guy on top were done like that with one of my favorite brushes set to clear. Erasing is so often blunter and uglier than what you want.