also, try doing it in steps.
- bounce at a height that you are comfortable with and will not limit your spin for the cork
- try doing a 180 to stomach drop
- 270 to stomach drop
- getting comfortable with the above, go to your back instead of to your stomach
- once you land on your back roll over the shoulder you originally span over to continue up to your feet
- take the whole thing to air when your comfortable.
when i first learned corks, i did a superman 270 to misty 450 ish. this helped with air control and sense.