(caution this my hurt the shoulder or hip)
1) Find a good long landing the longer the better with a good sharp Knuckle.
2)Find your speed. Do a couple passes and find out how much speed you need to jump from about 5-10 feet back from the Knuckle to the middle of the landing. just high anoph to clear it. Be careful you dont go sending it to the flats.
3) Now feeling good about your speed try doing 180s over the knuckle.
4)feeling good about 180 its time to move on. Start getting lower and lower on your 180 to the point you can almost touch the knuckle as it goes by.
5)understand the trick. The point of dragging your hand is to re-direct your feet from going over you head and getting away from you. There's no reasion to jump 3 feet in the air then you cant reach the ground this trick just skims the knuckle
6) now get low and as your coming in think about letting your feet get out in front then your going to pull them back down to the landing your arm and squeezing you abs side ways. at first its going to seem quit gay. but as you get more comfortable youll find you can go faster and deeper.
think smart dont go to fast and send a huge horizontal dead sailer to the flats. like all tricks its about timing.
watch some in the moves and compare it to these notes. study the trick look for key things like contact points with the snow and where there head is looking.
by being safe