What shoes would be good for an ollie (skateboarding) ?

comfortable shoes are best, really you can skate in almost anything but a good skate brand shoe would help. Vans are fairly cheap and a really nice brand, can usally find a pair on sale some where. The board sliding up isn't due to your shoes though, it's the angle of your slide and your timing. Just keep working on it more it can take a lot of practice to learn a trick the harder and longer you work the quicker you'll get it.