1) Do not stand near the front and shout conversations at your mates when the band is playing. Even if it is the support act. Talk between songs or go to the back.
2) If you must go to the bar and buy a round of 4 or more drinks, don't try to carry them through the crowd in one go. Do it in 2 trips or take a friend to help you.
3) If you have a weak bladder or intend to drink loads don't insist on standing right down the front. Stand near the bar/toilet.
4) No mobiles and that includes talking blurry pictures that you'll look at the next day, realise are shit and delete.
5) If you are over 6' tall, don't plonk yourself in front of someone who is less than 5'4". Same goes for people with big hair.