said it before, but i'll say it again:
you don't need us to tell you what trick to try next man. i guarantee that once you're out there on your skis, you'll feel more comfortable trying certain tricks (basically endless possibilities of tricks to choose from) than others, so learn those ones! and once you've learned those, then scare yourself a little with the stuff you don't want to actually try as bad, but still would like to learn. confidence is key, but if you feel 100% comfortable trying something, then you probably aren't progressing too much.
but if you really need direction, then i would say start learning how to spin on boxes, and really learn how to set your edge (aka gas pedal, scissor, whatever), because that's key. and on jumps, as other people have said, 540, switch 3, backie, front, flat 3, etc. as you keep trying stuff, you'll probably gravitate toward one aspect of park skiing over the other (rails vs. jumps). so get good at what you prefer, but don't forget to push yourself in the other aspect too when you can.