Get your crew together early. No one wants to be late to the show because one person takes too long to get ready. Also, depending on the venue and the popularity of the act, you may have to park a far distance from the actual concert hall.
Bring cash. You never know what kind of problems could occur when you go to see a band play. Whether it be change for a pay phone or cash for a purchase from the merchandise tent that doesn't take credit cards, you may find that you need more than you expected.
Wear something comfortable. You want to look good for the show, of course, but if it's a good one, you'll be moving around a lot. That's not going to be easy if you wear high heels or platform shoes, so try to make a compromise between style and comfort.
Drink plenty of water. Of course, use your best judgment and don't drink so much that you spend half the show in the bathroom, especially since you may not be able to reach one if you're close enough to the stage. However, you also don't want to be one of those unfortunates who gets so excited and dehydrated that they pass out before the show is over...or even before it starts.
Push back. If you are attending a truly happening rock 'n' roll concert, people may shove you once the main act takes the stage. Crowd surfers can also indiscriminately kick fellow audience members in the head. Just remember to push back as hard as they push you.