The November 2015 Golf Digest has a cover article by Tony Finau with the same title as this post. The article reveals his opinion that the fastest way to get better is to get good with your driver and your putter.
Good advice. Even Byron Nelson once said, “If you can drive and you can putt, you can play this game.”
The driver part won’t do you any good, though if you can’t hit the green with your 7-iron. If you can’t hit the green with your 7-iron, you won’t hit many fairways with your driver. Might as well leave it home.
Change your swing so you can hit the green with your seven-iron, say, eight out of ten times. Then you can haul out a driver.
As for putting, the ones to practice are the 30-footers and the 3-footers.
Learn to get the ball close to the hole from a distance. Not doing that is the major cause of three-putt greens.
Then learn to get the ball in the hole from close in. Missing the short putts is the other cause.
Those two things sound obvious, but surprisingly they’re not.
The way to get better at golf is to be real good on the basics. The 7-iron and putting are the basics. Go get ’em.