Defense is 90 percent heart and 10 percent skill, and your success is determined by your will and commitment to the task. That being said, there are a few teaching points to remember when playing perimeter defense on the ball:
Remember to begin with your shoulders lower than the person you are guarding. We call this the shoulders game. By keeping your shoulders lower at the start and then continuously throughout the penetration and drive, you are more likely to get to the spot before the offense.
An Arm’s Length
Do not begin too close or too far away from the offense. If you are too close, they will drive by you. If you are too far, they will shoot. The best thing is to begin at least an arm's length away. It is appropriate to reach out to your defender if you are not sure whether you are far enough away.
Keep Steps Short
Never forget your footwork. Taking long steps often will hinder your progress while defending drives. Take shorter, choppier steps and remember to "push-pull" off your front foot.
Remember the Hands
Another key is to have active hands. While on the ball your hands are busy, but you must also remember to use your hands while defending the penetration. Use a "deflection hand" high and a "ball hand" low and up on your defender. A lot of coaches will call this "riding" a player out. While you are defending the drive, try to poke the ball out with your ball hand, and then use your deflection hand to block passes or quick shots.
Another important hint is to never hit down on the ball. When you swing down on the ball it is a more aggressive motion and more likely to get attention from the officials for a called foul. Swipe up on the ball.
Get in Shape
The most successful defenders will have strong core muscles. Your hips, abs and buttocks will be strong and help you be balanced and able to move quickly in lateral motions. Jumping rope will help your foot speed.
The best way to become a great defender, of course, is to know your opponent. Watch film and read scouting reports. The best defender is the smartest defender.