start out doing airplanes to the tramp, 360 to back drop, then once you get that start doing them so you land on your back 90° to the side of where you originally landed. Then start taking it even farther around to a little past 630 and land on your hands and knees. After that the next progression would be to take it to your feet. The take off is the most important, the initial take off for a cork is actually very similar to a flat spin. You need to drive your outside hip up in front of you and to the side. It can be argued that corks and flats are actually the same trick, only in a cork you would have already spun a 360 by the time you reach your apex, where as in a flat most of the spinning happens after the apex. That being said when you take off you want to initially be looking in front of you, then as you bring your hips up and around look at the tramp at 180. After this you essentially let your take off do the work as you come back around to your feet. I realize that may not have been worded in the best order but hopefully that will help.