The two biggest things to understand when you're tracking the ball as a defensive back is your position on the field and understanding that once the ball is in the air you become the receiver. Too many young defensive backs worry about the receiver catching it or what the receiver is doing instead of focusing on what they should be doing. Just go out and make the play yourself, don't worry about him. Know where the ball is and attack it. Put yourself in position to bat it or catch it and make the play.