It comes down to trust. The guy behind you can see whats going on, you can't, so trust them to move around you, don't try to anticipate it and get out of the 'fast guys' way. Let them control the situation.
Ill echo the food comment, no need for cliff bars and small bottles. This is probably my favourite part about the velodrome, I've brought last night's dinner to eat in between session at long days at the track. Bring fruit instead of gels. Don't forget to drink water though, you don't have a bottle you can sip every 5mins on your cage, on a hot day make sure you are coming off and drinking, its easy to forget!