Also, remember the key to throwing a good change is making it look like a fastball. If you more or less throw a normal, not overpronated fastball, and then come with a pitch where you turn your wrist halfway around, the deception is lost. Weaker hitters might not pick up on it, but it would be a shame if you came to rely on this pitch, reach a higher level of play, and suddenly get killed by hitters who tee off like they know its coming.
For example, Dice-K's changeup had ridiculous movement on it last year, but he pronated so hard that nobody was fooled. This year hes sacrificed some movement and its been a far better pitch for him.