One of the best golf swing instructions is to learn how to test the correctness of your ball position.
The reason why learning how to test the correctness of your ball position is one of the best golf swing instructions is that a fraction of an inch off the ideal ball placement can change an otherwise straight golf shot into a curved one.
When using any of the Locked-In Golf™ Techniques to hit a golf ball on a straight path, if the sweet spot of the club face is centered as near as possible to the back of the ball (within one-eighth of an inch to the back of the ball) and the shoulders are aligned perfectly parallel with the target line at final address, an ideal ball position should exist.
Although I encourage golfers to use the Arrow Alignment Technique™ (that is discussed in several of my books and articles) to align their shoulders parallel with their target line, they nonetheless should test the correctness of their ball position before commencing their golf swing in order to hit the golf ball straight.
The test I recommend to test the correctness of your ball position is my Locked-Knees Test™.
Here are the the instructions to conduct the Locked-Knees Test™.
Once you have performed one of the Locked-In Golf™ Techniques, centered the sweet spot of your club face as near as possible to the back of your ball and aligned your shoulders parallel with your target line– the imaginary line running from your target back to and through your ball– simply straighten your legs and lock both of your knee joints without moving your ball in the process.
Then raise your shoulders upward very slightly and observe the spot to which the sole of your club face is aligned in relation to the back of your ball.
If the sole of your club face does not move backward from your ball or forward (on top of your ball) but instead, remains perfectly positioned as near to the back of your ball as possible, it will indicate that you have an ideal ball position.
If so, ensure the sole of the club face is grounded, keep your left heel planted, maintain eye contact with your ball and execute a simple golf swing without any attempt to manipulate your club off its pre-swing alignment and path during your swing.
Your ball should fly on a straight path in the direction of your target, discounting wind conditions and elevation differences between your stance and your ball.
However, if your club face does not remain firmly in place and, as near as possible to the back of your ball, when you lock your knee joints and raise your shoulders upward slightly, you should adjust your stance by moving your right foot inward or outward until the sole of your club face remains in its “near as possible position behind your ball” when the test is conducted.
Then, when there is no movement of the club face when the test is conducted, ensure the club face is grounded, keep your left heel planted, maintain eye contact with your ball and execute a non-manipulative golf swing.
Your ball should fly on a straight path in the direction of your target.
It may take some time to master the Locked-Knees Test™ to determine the correctness of your ball position but, once mastered, you should agree this to be some of the best golf swing instructions ever written.