In order to do rodeos/flats/corks you'll wanna be able to get backflips and sideflips (Lincoln loops, as they're called in skiing) to your feet.
gradually blend Lincolns and backflips into a flip right in between the two. Start grabbing Japan and you'll have what most folks call a flat 3. The more inverted you get, the more it resembles a rodeo, and at that point you should start to spin more. Rodeos are really fun, easy to add grabs to etc.
corks are more spin than anything, throw for a 7 or a 9 and dip your leading shoulder behind you. Spot your opposite heel as you rotate. You might get discouraged at first because you don't have the right balance of spin and flip or can't get them around.. Just keep at it and you'll be whipping em out all day err day.
hope I helped, if not check out the search bar or trampoline cult.