This one goes out to all the people in the stands at F1 night races, concerts, or sporting events:
Turn your flash off.
If you leave the flash on when you’re trying to shoot a football game fifty metres away, all you’ll illuminate is the back of some guy’s head. And then your camera will turn down its exposure because it expects a big burst of flash, so you’ll end up with an underexposed, muddy mess.
The only time you want to use flash is if you’re shooting something (or someone) close to the camera. If you want, you can then pull stunts like setting a long exposure time to capture the background, while using flash to illuminate the foreground (hi Sazz, hi Ealesy).
Also, if you’re in the middle of a mob of amateur photographers, move occasionally so other people can use the good sightlines. Especially if you’re holding up a phonecam in the middle of everyone’s shot. Cheers.