You need to wear a helmet. No compromises. Get one that can protect the back of your head for those times you take a backward tumble from your bike. Gloves are necessary, too and they will protect your hands from both the grips on your bike and the concrete (or dirt) when you fall. To avoid potentially getting injured in either circumstance, it would be best to wear some knee pads and elbow pads because, after all, the more protected you feel under your gear - especially during uncertain circumstances like these - the likelier it is that you'll feel ready to attempt that trick that's been eluding you.