Most of us start on an oldschool and then as time goes on you realise the bike is limiting you and you spend half the night tightening things up.
Eventually you end up on a newschool as you get more confident. I rode my newschool off every quarterpipe in there last night and i've been attending these private hire nights for a couple of years now, but my oldschool bike has only been hung up for about 3 months.
Most important thing is bring a bike with decent ramp tyres and ask for advice on how to ride - we all started somewhere and most of us will explain the basics and get you rolling.