One of the most important and overlooked aspect of putting is your posture at address.  This can have a direct affect on how your shoulders work during your stroke, and therefore, the path of the putter head.
A couple things we will need to check to see if your putter and body posture are a good fit… eye/ball alignment, putter/ground interaction & spine angle:
In our first test, we will need 2 golf balls…one for the ground to setup to and a second to test your eye to ball alignment.  Once you have taken your address position, hold the second ball right in front of your eyes and let it drop straight to the ground.  Your eyes should be 1″ to 2″ inside the ball.
The second test is to ensure the sole of the putter and the ground are interacting properly.  This is a simple check to make sure that the sole is flat to the ground and neither the heel nor toe of the putter are off the ground more than the other.  Some putters have slightly curved bottoms so you must have equal parts of toe & heel off the turf.

Chances are, if you’ve already passed the first two tests that your posture is good and the putter fits your body and stroke.  We do still have to take into account your spine angle as some can accommodate a poor spine angle with poor arm alignments.  We must make sure that your spine is neutral… as opposed to having a rounded C shape or an arched S shape.  You should also not be severely bent at the hip but more erect in nature.  Not vertical but somewhere around 60*-70* degrees depending on the person.

If you have now passed all three tests, you should be making some wonderful strokes and rolling the ball at your target.  If not, we should take a look at the putter itself to make sure it isn’t hindering your success.  Too often I see people with putters that are too long which makes it impossible to achieve proper posture and arm alignments.  This will make it extremely difficult to create a repeatable stroke with great speed control. 

If you’ve having any problems with your putter, posture and fitting are the best place to start!