The way I learned them was slide the rail, and near the end I'd just sort of look down at the rail behind me, thus you start your rotation. You're almost certain to land backseat everytime doing this, but after a couple times you'll get the whole spinning part down which is the hard part.
After that you can start to edge in and pop off to spin, eitherway I think spinning a little on the rail and basically not even popping can look way steezy especially if your going fast and just make it look fluid.
Also, definitely don't be afraid to start blindside. I'm glad to say I can finally 270off blindside on command now, but I'm not nowhere near front side 270s off. I think it's cause I have my right foot edge the foward side of the rails, so spinning to the right/natural way/front side is nearly impossible seeing as me pushing off spins me the otherway. Edgeing in is definitely key, I don't know how its described but when you hug the rail with your skis, one \ one /