Your technique for big jumps should be exactly the same as small jumps, except you don't have to huck to get spins around.
That said, your risk goes up if you get the wrong speed (as others have said) because knuckles and overshoots hurt more on bigger jumps. So it's a lot of making sure you get your speed right.
Make sure you can stomp 360s and 540s 9 times out of 10 before you take them to the bigger 30+ foot jumps.
Learning curve from 540s to 720s and up is pretty low (as long as you REALLY have your 540 technique down), it's just about spinning a little harder and getting used to continuing the rotation.
Once you have your spin technique down and get used to big jumps you'll honestly find them easier than small jumps because the run-ins and landings are usually better maintained than mini park jumps.
Oh and one more thing, if you have 360s and 540s down in one direction, you probably want to start working on rotating other directions otherwise it gets harder to do later when you're too used to only spinning one direction.
Honestly, don't rush your learning too much. Take time to cement in those basics.
I know everyone wants to say "I can do a 720" but it honestly means jack if you can't do it smoothly 9 times out of 10. Anyone can do an ugly 360 or 540, but smooth spins and style are another matter.
Last edited by Jed; 01-07-2013 at 06:47 PM.