Just dabbling in a little of this myself. I feel it most strongly going backward and rotating into it, and that's about as far as I get with that, and I'm sure someone will come along and be too eager to expound upon this, so I'm yielding the floor. Victor Veyrasset explains it best, followed by David Hamilton, but I prefer to watch Victor- DVDs can't look disdainfully at you and send telepathic "Don't quit your dayjob" vibes.