Taking photos at a concert seems like a hard thing to do, so that is why I've decided to try and help by giving you a small technical advice set.
Either you have a phone, a compact camera or a high end dslr, one creative person can take really good photos at a concert. I usually have my compact camera with me for several reasons: the security stuff won't pick up on my small camera, it's lighter and easier to carry and hold in a single hand, people will tend to act naturally in front of such a camera because most of them are having one of their own. There are many small and compact cameras that will shoot raw files and will almost match the quality of a dslr: sony nex, canon g1x or g15, nikon1, olympus pen, panasonic lumix, fuji xm1, samsung nx, etc, so using one of those will let you enjoy the concert and also take some photos. Have you seen those staff photographers carying two dslr bodies with large and heavy tele lenses mounted on them? They are not dancing that much. :)
If you don't have a good compact camera or you just don't want to carry it, you surely can use your mobile phone to take some photos. And no matter what camera you're using you should get as close to the stage as possible.
There are several issues that might encumber your work when taking photos at a concert:
Stage lighting is usually very dynamic – this means it will change a lot during the show.
The low light and low stage light that will force you to use a high iso.
The poor focus performance caused either by the lack of light, by the dynamic light or by the light that comes directly into your lens.
I will approach each issue separately and try to have it fixed by giving you an alternative or a way of working/shooting at a concert.
In order to have the subject in focus one can use a lens hood (if available) and try to focus on the suject when the light allows you to do it – wait for those lights that come directly into your lenses to switch off.
If the backlight switches off and you have the subject in focus, you can then wait for the backlight to switch on again and take the photo – lens flare may give a beautiful visual effect.
Most of the modern cameras, compact or dslrs have a good high iso performance. Besides that, the technical requirements for editorial images are not that harsh like the regular RF images are. So, a 800-1600-3200 iso can be easily acceptable – we are not asking you to take some 1000w/s flashes to the concert in order to have a technically perfect image.
Achieving a correct exposure is rather hard if you're not
using the manual setting for your camera. You should make
several exposure attempts by setting the iso, time and aperture and see in what lighting conditions these setting will give you a good image. I usually watch the stage lighting, set my camera exposure and then wait for the stage lights to be in the right place and take the photo. This means that you should watch the lights movement and wait for them to be in the right spot. When the things there are really dynamic (remember those strobes?), you should consider shooting bursts of images.
Other various things to take into consideration:
the image stabilization will compensate the camera movement but it will not compensate the subject movement, so make sure you use a fast exposure time whether you have stabilization or not.
Being close to the stage helps catching the right expression but will also change the view angle. Sometimes, being too close to the stage will mean that you'll shoot from frog's viewpoint and this can be quite unflattering for the artist/singer but can also put them in a majestic pose. Make sure you check your portrait guides book in order to avoid strange compositions – you want to have the artists look good in your images.
If needed, you should have a monopod instead of a tripod. It will give you much more flexibility.
Do not use a flash, it will spoil the atmosphere/lighting. With today's camera performances high iso should be preferred.
Last, don't forget to be creative. As always try different angles, when close to the stage you should take some photos with the audience as seen from the stage – the crowd will look great under those large strobes or floodlights. If you're using a mobile phone make sure to use each of those apps features for your advantage (panorama, hdr, timelapse and don't forget that you are connected to internet and you can send us the image in real time). Capture stage details (shiny or silhouetted intruments), people dancing and having fun, atmosphere surrounding the event, let the music open your mind. :)
Also, make sure you read the terms on the tickets, some concerts/bands are really restrictive regarding the images taken during the concert. If you need an accreditation, you must send the application yourself, and we can send you an endorsement that can help you get an accreditation if needed.