Watching some top amateurs playing with some top professionals, I noted one particular point: The back-swings of all the amateurs were similar to those of the pros, but the finish of their swings was not the same at all. None of them followed through fully.
Most of them had a pretty full finish. But none had a professional finish. There was the difference.
Now the professional finish - something everyone can note for themselves on TV - is unforced. It happens naturally. It HAS to happen.
The club swings out and up and in and back over the professional's back. Gary Player sometimes even swings himself off his feet. Perhaps it might be explained like this: on the downswing the player swings the club; on the through-swing the club swings the player.
Now this is the only kind of follow-through worth having. It is no good placing oneself in the correct position after the ball has gone. The finish has to happen because it cannot be stopped. It has to happen because it has to happen.
So how is one to acquire such a finish?
1. Understand that the second part of the swing is longer than the first part. The follow-through is much longer than the backswing or the downswing. (Both those are the same length, of course.)
2. Practice even on very short shots making the follow-through longer than the backswing.
3. Practice this with a putter on the greens.
4. At home, without a club, swing back and through again and again to get the feeling that the through-swing is twice as long as the backswing.
5. Exaggerate this feeling, while at the same time keeping perfect balance.
In short, make a full finish natural, and your natural finish full.