Know where you are on the approach at all times for your strike ball and your spare ball! Just like coordinates on a map, locations relate to your body build and to the path of your ball. You cannot just stand in an arbitrary place and roll your ball toward an arbitrary target without it interfering with the quality of your delivery!
For any given shot, put your body in a position which ensures accuracy and consistency in the path of your ball. You accomplish this by understanding APPROACH COORDINATES which involve two dimensions -- (1) how far you are away from the foul line and (2) how far left or right.
COORDINATE 1 - DISTANCE FROM THE FOUL LINE
This coordinate involves how far from the foul line you take your STANCE, or "SETUP." Although often-ignored, this critical factor determines how well your footwork fits your swing. If you stand too far back, your steps will probably be too long, and your swing will be hurried. If you stand too close, you will cut your last two steps short, losing accuracy and lift during your release. Once you determine the best length, you should not have to change it, with the exception of fine tuning.
HOW FAR SHOULD YOU TAKE YOUR SETUP FROM THE FOUL LINE? One word of caution -- do not use the traditional method of "pacing off" the approach and adding half a stride for your slide! This will position your setup too close to the foul line, giving you too little distance for an effective shot. The following method is more reliable for determining an APPROACH LENGTH appropriate for you.
Assume a setup position, but with your back to the pins and with your heels approximately two inches from the foul line. Without a ball, take a simulated delivery, using walking steps and end with a deep knee bend and a slide. Then, look down to see where the toe of your sliding foot has stopped. This is the place where the backs of your heels should be during your setup. This method should give you the proper length to your approach for a low-hips/high-leverage body position during your slide.
COORDINATE 2 - LATERAL POSITION, LEFT TO RIGHT
This coordinate determines your ALIGNMENT for strikes and spares. If you were to roll your ball from your setup position without taking any steps, your ball would follow a path determined only by the direction of your swing; the path of your steps would not be a factor. However, since under normal circumstances, you take steps to the foul line, you will always need a lateral starting point and a direction to walk for a particular ball path.
Your desired ball path is your desired TARGET LINE. For accuracy and consistency, keep your SWING PLANE, the circle made by your ball in the swing, aligned with your target line. When you walk your path to the foul line, your body's center of gravity -- it's CENTERLINE PLANE -- traces an imaginary line on the approach; we call it the APPROACH LINE.
To keep your swing in line with your target during your approach, your approach line and target line must stay parallel with each other during your approach. We like to say, "Walk alongside your swing -- never toward it, never away from it!"
Use the dots and arrows to choose what path you want your ball to follow. Then line up your bowling shoulder and your ball with the ball path, then square your shoulders 90 degrees to the ball path. Finally, push your ball toward your target and walk toward your target. Bowling consistently will be much easier.