Grip on the sinker

Question
I've heard many different ways on how to grip the sinker, I would like to know how you would grip one and what to do to put more movement on it. I'm 16, i would like to add the sinker to my commanding fastball and slider.

Answer
A sinker is a tough pitch to teach. some people will never be able to throw one.
here are few guidelines for you to develop a sinker of your own.
1. start by learning a two seam fastball. this can be thrown with your fingers (index and middle) with OR across the "sweet spot". The sweet spot is where the seams are closest together.
let the grip give you the movement. throw every sinker like its your 4 seam fastball. this means that you don't try and make the ball sink by turning your wrist over at release. the best sinkers have late and sharp movement.
2. when you get a feel  for the 2 seam, start moving your thumb from under the ball to the side. this will decrease the speed and increase the movement/sink.
3. continue to tinker with your grip and grip pressure, doing your best let the grip give you the sink you desire.
good luck

Jon