Uploded this 'casue ElohJay asked about setting flats and I've got a clip in super slo-mo which helps to learm a lot (IMO).
The set for a Flat is basically a Lincoln but you rotate and look over your shoulder in the direction you're spinning.
But.. its kind of different to a bunch of other tricks in that you let the jump set a lot of the flip.
One of the most important things with a flat is too let the jump take your lower body up from under you; you've got to be patient off the take-off. If you look at my body position at take-off I'm not upright, my body's in-line with the jump.
Hope this helps.