If you can get a friend or two to learn them with it helps. But it's one of those tricks you just have to send. Some people learn front flips first, some people backflips, some people cork, some people can do all of those, some people only 1.
If you can do it on the tramp you can do it on skis. It's just getting the balls to send it.
I think poppy and short park jumps are the easiest but you're at the mercy of where you ride. If you build your own make sure you get a bit of height. Front flips are less scary for a lot of people because you can just kind of tuck and roll forward. As long as you clear your head you can land on your back and it doesn't hurt too bad if it's soft ish.
Backflips require more commitment. You need to get at least chest height air imo. You can learn them with less but it's sketchier in terms of catching tips.
For backflips the less forward momentum you have the better. Small stepups, windlips, decking out on hips are all really good options for learning. Just make sure you commit and go straight back, look directly back behind. If you twist that's how it goes to shit. If you've done it on a tramp, and commit, you'll probably land or almost land.
Personally sucked at corks kind of and never learned them on skis. Sorry. That comes down more to having spins locked down and dropping your shoulder.