You putting stroke is not unlike your full swing. It is still a shot that is played to the side of the target line which means the club is swinging on an arc. It might be a slight arc but it is an arc none the less. So your posture becomes real important in allowing you to swing your golf club. In your putting stroke here are some of the key elements that you need to think about from a posture standpoint. You are going to bend from your hip joint, so first identify where your hip joint would be, which is where your leg would bend from. You are going to push back from your hip joints until your arms can hang away from your torso. You have now put your arms in a position where they can swing and they can swing freely because your arms are underneath the suspension points of your shoulders. By pushing back from your hips it keeps your back nice and straight so that you can turn around your spine ever so slightly to be able to make the stroke swing on an arc. Your weight on your feet, this is very important, needs to be distributed between the heel and the ball of your foot, we are going to call it right on the arch of your foot. That is where you want to have your balance point. So it would be easier to feel like you are going to tap your heels on the ground instead of your toes. Push back from your hips allows your arms to hang away from you. Have a slight knee flex, if you get too much of a knee bend all of a sudden that changes the way your spine is to the ball. Knee flex, put your arms right underneath your shoulders, put your hands and arms in a position to swing. Give this a try. I know these fundamentals will help you improve your putting.