1. Dress accordingly.
"What am I going to wear to this show?" is always in the back of my mind the second after I buy my ticket. It really depends on what kind of concert you're going to. For example, if the show you're attending has assigned seating -- awesome! Wear nearly whatever your heart desires, weather permitting. If you're attending a general admission floor concert, good luck. Wear something comfortable that you're willing to sweat in, or potentially ruin, practical shoes, and light weight clothes. No sweaters or jeans, unless its winter.
2. Plan ahead.
As soon as tour dates are listed, talk to your friends. Figure out who wants to go, who can order the tickets, and who can drive. Having a stable plan for getting to and from the venue is key, especially if you haven't been there before, or it's in a rough area. It's incredibly stressful to try to plan last minute, or have your plans fall through.
3. Do your research.
After a band or artist starts the tour you are seeing them on, look up the set list (unless you want to be surprised). Likewise, look up their opening act's set list, and familiarize yourself with their music. Look on the venue and band's websites to see if CD signings are taking place, what time doors open, and other additional information. Also, find out the rules of the venue: if you can take in water, what they check for at security, if you can brings signs, or if you can bring gifts for the band.
4. Be prepared to wait.
If you're taking a day, or even a few hours, out of your life to go to this concert, don't get angry or frustrated when you find yourself standing around. You wait in line outside the venue to get in, you wait while the crew sets up, while the crews changes sets between bands, and so forth. Don't be surprised if the headlining act doesn't go on until hours after the show starts.
5. If you want to meet the performers, be patient.
Suppose your absolute favorite band is coming to your town. You buy tickets immediately and tell yourself, "This is the time I will finally meet them." Make a game plan for you and your friends. It will, most likely, include hanging around the venue all day. Get there early to catch them leaving their tour bus or setting up, and hang around their bus after the show. Nearly every artist that I've seen (with the exception of major names and stadium shows) will meet fans that wait by their bus until midnight or later. They appreciate your dedication, and you will be rewarded at some point.
6. It's okay to go alone.
I know it seems majorly embarrassing, but if your friends aren't interested or can't go, go alone. That being said, be safe. Obviously, don't walk far distances alone or talk to sketchy strangers, but feel free to rock out by yourself. Honestly, when I go to general admission floor concerts, its a struggle to keep your friends with you as you're rocking, dancing, and pushing your way to the front. Have fun and enjoy yourself, no matter who you're with.
7. Don't worry about being too into the show.
There are always those people in the crowd who just stand there motionless while watching a band perform mere feet from them. No offense, if that is you, but I am not that way. I'll dance, sing, and scream my heart out, and I get a lot of nasty looks from others in the crowd. No matter what type of concert goer you are, accept everyone around you.
8. Buy merchandise before the show.
Get to the venue early enough to stand in line to buy a shirt or a poster before the show. After the show, the lines are horrendously long and they might sell out of whatever you want to buy. Also, plan ahead what you want to buy. Look online to see what tour shirts are being offered, and if you really want to guarantee yourself a shirt (especially when seeing a big name artist), buy online and pay the $5 for shipping. Trust me, it's worth it.
9. Be safe.
This statement covers many areas: stay hydrated, trying to get fresh air if you feel sick, and try to make the charge on your phone last so you can contact your friends. If you feel sick or need help, let the others around you know. If you're near the front, the security guards by the barricade will help you get out of the crowd. Drink mass quantities of water, and you should be fine.
10. Have fun.
No matter what happens at your concert, try to make the best of it! Remember why you're there, enjoy yourself, rock out, have fun.