The better grip you have on the ball, the more you can control it. The key is to add some topspin, so the laces on the ball create wind resistance, causing the ball to lose altitude.
With your thumb underneath and your index and middle fingers together, grip the ball across the seams that have the widest distance from each other. Hold it tightly, especially with your middle finger, but don’t let it touch your palm.
Keep it secret
Don’t let your grip give away your pitch. Keep the ball hidden in your glove as long as possible while throwing.
Wind up as you normally would for a fastball, but concentrate on the angle of your hand. If you are right-handed, your palm should be facing first base as the ball goes over your head. If you are left-handed, it should be facing third base.
Snap the wrist
As you throw, keep your wrist cocked and rotated toward your body until you release the ball. At that point, turn your wrist and snap it down. Keep practicing until you find the correct release point for you.
Don’t forget to follow through
The back of your hand should face the batter as you let your throwing arm swing across your body.