Harvey Penick is one of my favorite teachers of all time. His methods were revolutionary and have stood the test of time.
If you practice Mr. Penicks perfect swing in slow, I mean super slow motion. Like when you think your going too slow, go slower!! You will develop the muscle memory to repeat this perfect swing on the golf course. (Muscle memory is only an expression)
Things to remember. Stay positive, a Good grip is imperative, take dead aim, focus on the ball (in this case blade of grass) and don't watch your club swing back you will develop bad habits. Focus on the points outlined below, in the quote from Harvey.
The Mythical Perfect Swing"Here is how to make the Mythical Perfect Swing that all golfers are always pursuing:
Stand a few paces behind the ball and look down the line toward the target.
Walk to the ball from behind, get a good grip, pass the club back of the ball square to the target, then adjust your stance to fit.
Have a slight waggle and then set the club back of the ball again and make a forward press similar to what you would do swinging a bucket of water.
In the first move back as the club gets parallel to the ground, the toe of the club points directly up, and the left heel starts off the ground.
Let the club come up, keeping your elbows in front of your body, to the top of your backswing, where the clubhead will be pointing almost to the ground.
Return your left heel to the ground and simultaneously let your right elbow move back to your side as it comes down.
Weight has started shifting to your left side. Your forearms cross over as they swing. Your head stays behind the ball, perhaps even moving slightly more behind it.
Finish with your forearms in front of you. A good finish shows what has gone before it. Let your head come up to look at the good shot..."
I think the real key here is repetition of positive thoughts. Think perfect swing all the time.