Hi there and welcome to the Q&A Forum,
- First, I recommend watching your white balance setting. Your camera, like many others, does not have the best Auto White Balance settings under artificial light. So take test shots using different white balance settings. Watch the changes on the LCD until the color looks right.
http://www.digicamhelp.com/taking-photos/advanced-techniques/white-balance.php- Depending on how the scene is lighted, I'd use spot or center weighted metering. Again, take some test shots to checl the results:
http://www.digicamhelp.com/camera-features/camera-modes/metering.php- You'll probably be tempted to zoom in and shoot, but if you can, shoot at or near the widest angle. Your camera has a pretty fast lens at F2.8 and will let more light in than if you zoom. You can crop later when editing for a close-up view. Shooting at a wider angle will let you keep the ISO as low as possible, anything over 200 may be noisy. You may have no choice to shoot at higher ISO numbers and it's better to have noise than no photo at all.
http://www.digicamhelp.com/camera-features/advanced-settings/iso.php- It's also VERY important to keep the camera as steady as possible to avoid camera shake, even with Image Stabilization turned on. This will help prevent blurred images.
http://www.digicamhelp.com/taking-photos/basic-techniques/hold-digicam.phpA few other thoughts.
I recently bought the Canon SD870, somewhat in the same category as yours. The ISO performance has improved somewhat over my previous SD camera, the SD700. So I keep it on auto ISO for many shots.
I even find face detection better than expected, so use that when it's difficult to see the LCD or there is a lot of movement when I'm trying to photograph people.
The operative words in all these suggestions are to take test shots and, of course, become familiar with your camera settings before the special event.
Most importantly, enjoy the event.