One of the most important things about putting is to have your body remain more or less

"motionless". Your hands and arms should really be the only things that are moving during the stroke. A lot of body movement causes major mis hits with the putter, resulting in an inconsistency in line and speed. 

In order to eliminate body movement, try to feel "inward" when setting up. Feel as though your

elbows and knees are pinched in toward an imaginary axis running through the middle of your body. By feeling this, you can keep your weight centered and body quiet throughout the stroke. By keeping your body more still when putting, you can say good-bye to those pesky 3-putts!