Try ramps and such, unique jumps and see how high and far you can come. a tip: if you're on a bike, bash forward or slightly push the left analog stick forward to go even faster. After that, practice wheelies and grinds(wheelie onto small, thin rails and push forward to lock onto it). DL some tutorial vids, read some big FAQS like Gotups' or DeathCobra's(right?), they're of great use for beginners. Just try simple things first, then try something harder, repeat simple and harder ones, and continue with a bit harder again. Just rinse and repeat, it's quite handy.