Start From a Solid Base
Keeping your lower body stable is crucial to consistent putting. All of the motion on your stroke should come from either your hands or shoulders, not the legs. To check your putting technique, stand in your normal stance, but instead of gripping the putter, let it rest against your thigh. Go through your regular putting motion without the club in your hands. If the putter falls off of your thigh, your lower body is moving too much on the stroke.
Making Short Putts
Concentrate on the point of impact when hitting a short putt. Try to make solid contact and drive through the ball, keeping the club face square to the hole. There is a natural tendency to shorten the putting stroke on these shots because the player is trying so hard not to hit the ball too long. Practice putting with a short backswing to improve the follow-through of your stroke. This will force you to keep accelerating the club head through the point of impact instead of relying on the backswing to generate momentum.
Reading the Green
When setting up for a putt, the two most important factors are the direction and speed of the green. After kneeling down to get an idea of the slope of the green, aim for the high side of the cup on your putt. This will make the ball curve down and lip in if you are slightly off instead of lipping out and rolling down the green to give you another tough putt on the next shot. The distance a shot will break depends on both the slope and how hard you hit the ball, with harder hit balls breaking less.
To practice adjusting your shot for the break of a green, try the following drill with a partner. Find a practice green with a decent amount of break and set up a medium length putt. Hit this shot several times while your partner watches the path of the ball. Have your partner mark the point where the ball turns downhill with a golf tee. After a few shots, you will have several golf tees in a curved line, which represents the apex of the curve. Now try hitting some practice putts where you aim for the high side of the tees and let gravity take the ball down into the cup. Experiment with different speeds until you understand how each adjustment affects the path of the ball.