Definitely take a camera to keep all the lovely memories.
Try a cleansing face mask like a clay one which will give your face a nice lift.
Do a deep hair conditioner like VO5 hot oil to give it a nice shine.
A nice body scrub will leave you with a nice glow as well (provided you haven't put any tanning or such or which may rub off).
You can get some lovely products which give your face that bit extra for a nice fresh look, Clarins do a flash beauty balm which is fab but a bit pricey. There are cheaper ones on the market though, No7 do one and Botanics and there are often offers on in Boots for those.
As for the stops, jus tkeep your face lovely and clean, water as hot as you can bear on them and drink loads of water.
If all else fails there are some fab concealers out there, just don't go mad with them as it can make them more obvious.
Clothing wise make sure you're comfortable as well.
For the prom itself just relax and enjoy, don't let a random spot etc.... ruin what can be a fab night with some fab memories :)
Enjoy hon x