There are a lot of park riders out there that are trying things they are not yet ready for. The easy way to make sure your ready is by designing a progression to get to your desired trick. Generally the more scary a trick seems, the less ready you are for it... Some people may disagree and say that anything is really really scary at first, and while this is party true, here are some sample progressions after ATML:
First be sure to know ATML (or get wrecked)
Approach: Coming straight or from the side? Flatbased? On edge? which edge? knees bent?
Takeoff:Jumping? off both feet? off nose? off tail? off toes or heels or flatbase? riding on?
Maneuver:suck your legs up (almost always true), spin? with shoulders? or with scissoring feet? where are you looking? grab?
Landing: where are you looking to spot your landing? extend your legs to meet the ground, then absorb with ankles, knees, hips
Here are some progressions, basically try to break each trick into its most basic parts, make sure to master each one individually, then combine them. This will reduce chance of injury, and make you a better rider for it
Backflip (i include this because many people will say there is no progression and you have to just go for it)
1:Without the board
a) Trampoline? Or foam pit if you live near one, there's one in PDX for about $10
b) off a cornice into powder, still without the board into pow
c) into a pool/river
2: A jump you build into fresh snow, much less scary, and less risky
3: Try in the park when you know you can land it (you will know)
270 on (shin guards not a bad idea for any rail riding)
1: Get comfortable with 360's on small jumps and just jumping off flatground and doing a 360 (yes 180's first, all 4 of them) no rails/boxes yet
2:make sure to be extremely comfortable with boardslide/frontboard just by pivoting while on the box or jumping 90 on
3: 180 on then maybe 180 on 180 off
4: trying on a almost in ground flatbox with no gap to get on
5: very slowly build to bigger and bigger features
If you follow a progression each step is small, so it is never really really scary, because you have a greater chance of landing it, and the risk is minimized. Having said that, best of luck in the park!!!