Here are my top 5 tips for those beginning in concert photography:
1) If you fail to prepare, then prepare to fail
Study up! Before the event, research the band and venue. Are the entertainers active on stage, or do they mostly sit on a stool and strum a guitar? How well is the environment lit? Does it take place outside, inside, or a combination of both? You need to know these things in order to set your camera to the proper settings.
Shoot in manual mode. MANUAL EVERYTHING. This includes focus too. The last thing you want is to shoot with a shallow depth of field and the wrong subject is in focus. I suggest shooting with a lower f/ stop in order to let more light in. Exposing your camera to more light this way will create a nice shallow depth of field for sweet portraits, and you can crank your shutter speed high in order to freeze motion. The higher your ISO, the more noise your image will have, therefore it's best to manipulate with aperture and shutter speed.
Remember when I told you to study? Okay good, because since you studied, you know an epic moment is about to happen when the bass drops in 10 seconds. You HAVE to study. Having a feel for the songs helps you shoot with intent and be better prepared to capture emotional action shots. Listen. You only have one chance to capture the moment.