I didn't really learn it, hehe... I just started doing it. Just a tiny bit at the end of my brush (
this is pretty much my foundation brush), and I just apply it to where I need it. I ascribe to the "less is more" school of thought with foundation, so once those areas are "evened out," I take the brush with no foundation and sort of "cross-hatch" the rest of my face, so that I don't end up with any make-up lines.
I also like to clean my brush about once a week. I'm probably doing it wrong, but I use the same stuff I use to wash my face to clean it.