That's exciting! I shoot with a full frame Canon but started out with a similar camera to yours (only mine was also a Canon). From what I've read, your camera is a cropped sensor and not a full frame camera. So low light will be tricky, but still manageable. You'll want to learn how to take photos without a flash.
What lenses do you have? 18-55mm? 50mm? 70-200mm?
* Always invest in the best possible glass that you can afford. A good camera is great to have, but a fantastic lens can make a HUGE difference in the quality of your photo. There's always gear-heads who are selling their gear to buy the latest & the greatest gear, and you can score some great deals on used lens.
* Invest in a good camera bag.
* You'll want to play around with your aperture, shutter speed and ISO to compensate for the low light. Just remember that the higher the ISO the more noise you'll get in your image. Just because you can shot in a high ISO doesn't mean it'll come out pretty.
* A higher shutter speed will allow you to capture those fast moving images and help to eliminate the blurred hands, faces, legs, etc. With that said, the higher the shutter speed, the more difficult it is in low light because the lens is allowing less light in due to the speed and will make the photos appear darker (hence why you'll need to compensate with the aperture).
* The auto modes on you camera are good to begin with but to get the best chance at controlling the shots it's great to learn how to shot in Manual and get a feel for the features of your camera. When we shot in auto modes like sports, portrait, auto, etc the computer in your camera is making the decisions for you and could make the wrong one and ruin the perfect photo because it doesn't have all the information to make the best shooting mode decision (especially when we shot in low light at events like comp's). Only you will truly know the needed shutter speed, aperture, environment, etc.
* Definitely play around with the white balance as it will vary even when you go from shooting in the hallway to near the stage area.
* Check out YouTube and Lynda.com for some great tutorials to get you going.
* Try to shot in RAW and not in jpg. When you shot in jpg you are creating a compressed file of the photo and it's more difficult to edit the photo. RAW is like being able to open the file up and tweak everything from saturation, exposure, highlights, white and black tones, etc. So if you shot a photo and it's too dark, you can play with the exposure and lighten it up a bit to compensate.
