Stay near the front, but not on it- you'll get a lot less of the slinky action if you're in the first 15 or so riders. It can get all goofy near the back, especially with inexperienced riders, and really takes it out of your legs accelerating back up after every corner. And what snicklefritz said (both things) are good suggestions-- you don't want to spend energy mashing out of every corner.

I'm a lazy-ass trackie so I used to stay in a small gear and spin a little extra coming out of corners. Now I'm just too lazy to bother with crits, and stick to the track for racing, which is more addictive than crack. It distills away all the bits of the race where not much is happening and packs everyone into a smaller space with no shifters or brakes.