One of the most difficult things for golfers to understand is what position they need to be in at impact for a proper strike.
One plane impact position
There's a great drill for this. It's primarily for two planers, but if you're a one planer you can still work with it up to a point to learn and groove your impact position.
In the one plane swing - the Rotary Swing - your ideal impact position is head behind the ball, hips and shoulders open, right elbow staying back, and hands leading into impact.
Those are the basic pieces of a Rotary Swing impact. It's a very dynamic position.
That dynamic aspect is why this drill is a little less ideal for one planers.
Two planers have a more static impact position, so they'll really benefit from this drill, but you can still get the basic idea and hit half shots with it.
Hitting a full shot like this would be difficult and not very helpful for a one planer.
For the One Planer
The goal of this drill is to learn where your body and your hands need to be in relation to the ball at impact, and to practice coming into that position.
One plane impact
You want to be ahead of the ball and open to it at impact, so set up for the drill that way.
Preset your body into your ideal impact position: Head back, hips open, shoulders open, hands leading, and right elbow slightly back.
Swing back for a little half shot, come down through the perfect impact position, and rotate through.
Why can't a one plane golfer hit full shots with this drill?
The Rotary Swing impact position is not a static position. It's very dynamic, meaning that you're not returning to anything like the position you were in at address.
Rotate back for half shot
You're coming down into a completely different position.
You can't get yourself all the way back to the top, but you can still work on it and learn from it with smaller swings.
Get into your ideal impact position, take it maybe 3/4 of the way back, swing back down into the impact position, and release your body through.
Even though you can't use it as fully as a two planer, this drill is important because it helps you understand the fundamentals at impact.
For the Two Planer
Two plane impact
As a two planer with a more upright golf swing, you're trying to return to basically the same position you were in at address.
Your impact position is only slightly different than where you were at address. Your shoulders are square, your hips are slightly open to the target, your hands are slightly leading.
You're going to be a lot more square than the one planer. Your right arm is really extended out away from the body. You've got a lot of pressure or force generated from that right arm releasing.
When you get into the impact position you can go ahead and take a fuller swing back, then come down through your ideal impact position, hit the ball, and follow through into your release.
How Does it Help?
If you're able to get into the proper impact position, you can actually do all kinds of crazy things up at the top of your swing if you want to.
You can swing it way up and then drop it around, whatever you want, as long as you get down into impact with the right fundamentals!
You can make almost anything into a good golf swing if you get it right at the point where that club hits the ball, and you learn to do that by getting into the perfect impact position while you're standing still.
Teach your body, "This is where you want to be."
Both one and two planers should work on this drill, get a really solid understanding of what your body feels like and the sensations you should have at impact, and just watch your ball striking improve.