There should be different rules for classical, folk, "cool" jazz, and other concerts where the sound level is reasonable, and for rock or hip-hop or whatever concerts where the average person's pain threshold is exceeded on a regular basis.

In the former sort, I'd suggest as most important:

1) If you bring children too young to understand the need to be quiet, or with physical, mental, or emotional issues that make it impossible for them, or who simply have never been taught to (that last may include "children" of any age), be prepared to remove them - quickly and quietly - if they start to make noise.

2) Leave your cell phone home. If you can't stand to do that, leave it in your vehicle. If you are a doctor and are on call, or are the President and need to be accessible if there is a nuke launch, put your phone on "vibrate," and sit near the aisle so you can leave quickly and quietly if you need to answer it. A person who uses his or her phone in a concert of the less noisy sort should die a horrible and painful death, then go to hell for all eternity, and all of his/her loathsome spawn for seven generations the same.

There really aren't many rules in the latter sort. Perhaps, "If you kill someone, don't get blood on the people near you."

In Peace and Love, Peter