Some obvious and quite simple things below, even things you probably don't think about, but definitely helpful during the busiest of events. We dare you to find one you don't agree with!
Go to the toilet whenever you can (You don't know when you will get the chance again).
Eat and drink when you can (You don't know when you will get the chance again).
Wear different shoes every day (particularly on hard floors, it reduces foot fatigue).
Write stuff down. If you remember something you need to do or someone asks you to do something - write it down, otherwise it will be forgotten the next time someone asks you something.
Always carry an alarm clock, a spare phone charger and painkillers.
Be prepared for the worst (it will happen if you don't).
Want to learn, this will only make you better and set you apart from the rest.
Take responsibility - no matter how small your peers will appreciate it.