I'm not park rat (except this year). But I would start off with some straight airs, and try some basic grabs. I learned the 4 basic 180s on the hill before I took them to jumps and side hits. For me it was much easier to pop a 180 going sideways along a run then off a jump.
As for boxes and rails, being able to hit the ride on rails and boxes is a good start. I am a beginner though when it comes to rails, spent my time in the park last year on mostly jumps (3rd season riding)