sounds like you might have a rising fastball so 1) aim at a lower target. 2) grip the ball across the skinny part of the ball (where the space between the seam narrows). This will prevent the air from catching all four seams and the ball rising on you. 3) check your release point. have someone closely watch you while you throw and see where you are releasing the ball. Generally you want to release it out front and at about eye level to keep the accuracy max.