Well, the first way to do a 360 off a cliff is post a thread on NS. Since you have that part down, your ready to move onto step two.
Make sure that you have 360s on lock everytime you do them. Once your to this point, simply find a small cornice (ie a drop with no kick) and try them off of there. This will give you a good feeling for what it feels like to spin without the kicking force of a jump (because it is slightly different).
Once you can do that, then take it to slightly bigger drops. You will want to hit these on softer days, which means engaging your spin will be more difficult. This will make speed and commitment imperative.
Keep in mind. Baby steps!