don't land rear wheel first, it's cheating and looks rubbish.
As has been said, you need to look around with your head, this makes your whole body turn and makes it much easier, also don't stop looking, if you stop looking around with your head at the 180 point, you will come up short, keep looking until you have spotted your landing. Ideally you want to get nice and high and tuck the rear wheel up, the higher it is and more nose dived it is, the more stylish.
Oh yeah, obviously don't pedal kick into them, that's also cheating, bunnyhop or don't do them
I am a little scared of them, I have a nasty habit of nose diving too much and sending me over the bars.