Many of us hobbyists upgraded to DSLRs to get the best shots possible of our kids' activities. In your case, the teams' you follow. I've been shooting kids' sporting events and will simplify what has been working for me.

1. Aperture Priority, AI Servo mode, speed burst settings (most images you can get per second). shoot in JPEG instead of RAW.
2. shoot wide open (lowest f-stop your lens will go). if close to the action, worthwhile to pick up the Canon 50mm f/1.8, or f/1/4.
3. crank up your ISO to whatever it takes to get a shutter speed of 1/1000 of a sec.
4. shoot tight
5. crop tighter
6. lean on the shutter button for peak action (in cheer, when somebody jumps for example), take at least 10 shots. you MAY get one keeper. don't be discouraged if focus was missed or you get 0/10 keepers.
7. i dont use flash as this can interfere with the atheletes and performers.
8. shoot lots and shoot often. during a volleyball tourney or kid's soccer game, taking 500+ action shots is fairly common