This video will show you exactly how to Throw the 12-6 curve-ball. Key thing to keep in mind when practicing your 16-6 curveball:
1. Make sure it throws straight downward, it is an overhand curveball.
2. You should always grip the ball inside of your palm, not just your fingers, to achieve the best spin.
3. Straddle the lace between your middle and index fingers. Get a good solid grip.
4. Throw it similar to a fasteball but when you are coming overhead use your fingers and your wrist to pitch the ball straight down out of your hand to get a good top spin on your pitch. This also grants come deception to the batter since it looks like a fastball, its all in the hand, not the forearm.
5. Try to get the ball's rotation straight. The ball should go stright down, hence 12-6 rotation.