As a catcher, how can I improve the velocity of my throws to second base?
Coach Swift answers:
Focusing on good mechanics will improve your throwing velocity.

1. With runners on base, start with your right foot back a little. Then you do not have to make a quick step with the throw. 
2. Get the ball up above your shoulder and back in the throwing position without dropping your arm down to your side. 
3. Step hard and follow though. 
4. As you mature you will throw harder, but continue to work on proper mechanics. They will save you a lot of grief in holding or throwing out runners.