seriously, just look for a wave thats .5 seconds from breaking (once youre comfortable with it, you can do it in a wave that's just broken/whitewater also, just as easy, but mentally, the whitewater messes with me sometimes)..
as youre coming up the face of a wave, you dont need to be going to fast... as long as youre on a nice, comfortable plane, you have enough speed...
the trick is here.. as you approach the base of the face, GUN IT AND HOLD IT WFO AND DONT LET GO TILL YOURE AIRBORNE. try squatting down on your ski as youre going up the wave. your ass should be hanging past the back of your ski as you leave the wave. this will help give you alot of rotation as you are first learning the BF.
the other hardest thing to do is to remember to look back at the wave after you leave the water. youre going to want to stare at the nose of your ski (naturally)... try to break that habit early.. try to tilt your neck back and try to spot your landing ... this will also help you rotate alot more..
i still nose them in alot... but every once in a while, i'll get full rotation.
its a really easy trick.. its just all balls... the keys are:
1) fistful of throttle all the way up the face
2) tilt your head back
if you commit to those two things, youre doing a BF every time.
wave selection is also critical when you're first learning. try to find a nice, solid, vertical face. just makes it easier to learn.
.02