start with ground tricks (butters etc.) and work up to boxes then other jib features and rails. start catching air on rollers (outside the park) and other natural terrain. gradually find bigger features. eventually you'll be ready for the park even if you decide you're never going to send it on a 50-footer you'll be ale to get in there for a few laps and have a good time.
(I'm 32, didn't really start riding park until I was like 29)