Okay, first things first. You say you need to work on your control. I remember when I was a little snip, 12, 13 years old, and I would get a good catcher and we’d set up 60’6’’ apart, mark off a home plate and a pitcher’s rubber, and play a little game we called “ball and strike”. The catcher would position his mitt high, low, inside, outside, wherever, and my job was to get the ball smack-dab into the pocket of the mitt. This is more than just a drill—it’s a good workout, and what a satisfying feeling it is to hear the THWACK of the ball as it hits the pocket! I had a couple of pitches which I used at the beginning—a good curve and a palm ball, and later on a knuckle-curve; even after I got some more stuff in my repertoire I continued this drill.
There’s a lot of controversy concerning the age at which one should start throwing breaking pitches. I agree that for the most part one should wait till about 14 or 15 years old to start throwing a curve—but I was a natural sidearmer, and I had a decent curve ball that came attached to that delivery, and if you’re 12 years old and can throw that thing without screwing up your arm, go to it! I had no choice—I didn’t have a fast ball to speak of, so I had to go to the breaking stuff early and become a “snake-jazz” pitcher. And if you’re looking for a pitch you can use as a changeup, let me suggest that you try the palm ball, which is thrown with the same motion (and the same arm speed) as the fast ball.
What you do is grip the ball way back in the palm of your hand, with the thumb on the bottom and the other fingers on top of the ball—the placement of the seams doesn’t matter all that much. The thing to remember is DON’T TRY TO SQUEEZE THE JUICE OUT OF THE BALL!—otherwise when you throw it the ball will just squirt out of your hand and drop to the ground with a plop. You can leave a little space between the ball and the palm of your hand, and grip the ball firmly. And you can loosen up on the grip as well, which will slow down the pitch. I used to use that pitch as a changeup, and a nice one it was. 8)