To consistently hole a lot more putts, work at maintaining the in-line forearm position and even-paced stroke shown here.
1. SET YOUR FOREARMS SQUARE
Bend your elbows and rest them lightly against each side of your rib cage, so that your forearms are in line and parallel with your target line. When viewed from behind, it should look as though the shaft is an extension of your right forearm and is pointing toward your right elbow. Get your forearms in line and the putter will follow them right down the line during your stroke.
DRILL: LINE 'EM UP
To ensure perfect forearm alignment, stand up straight and hold the putter horizontal to the ground, so that it's in line with your forearms. Both elbows should be tucked into your sides. Now bend slowly from your hips and gradually lower the putter to the ground, simultaneously bending your knees. Make sure the putterface is aligned to your target line, and you're ready to go.
2. KEEP YOUR SPEED CONSTANT
Picture a pendulum swinging back and through, and note how the length of the backswing and follow-through are the same. That's exactly how you want to swing your putter. This will encourage the putterhead to travel at an even pace and reach its top speed just before impact, not after. Too many golfers try to add acceleration at the ball, which can lead to a "yippy" stroke and poor distance control.
DRILL: DON'T CRASH THE GATE
Stick two tees in the ground so that they form a gate just wide enough to allow the ball—but not the putterhead—to pass through. Now place a ball behind the tees and make your stroke. You should find that even though the putterhead can't accelerate past the ball, the ball will still travel at the desired speed and distance. Work on this drill from a variety of distances to consistently dial in the correct speed on all of your putts.