We all miss more putts than we think we should. A lot of times it is simply due to the fact that our eyes are out of position. If our eyes are too much inside the target line we will actually see the hole to the right of where it actually causing the ball to be hit toward the toe of the putter as we attempt to pull the ball toward the hole.
Conversely if our eyes are outside the target line we see the hole actually left of where it is causing putts hit toward the heel of the putter in an attempt to push the ball into the hole. Putts not hit in the center of the clubface also do not have the energy of a putt hit on the sweet spot causing major distance control problems. There are two really easy ways to check and correct where your eyes are at address.
The first one is to use a large mirror and put a 12 inch piece of tape on the mirror. Place a ball on the tape, take your set up and check where your eyes are. They should be slightly inside the tape but parallel to it.
The second way is to take your set up and place a ball on the bridge of your nose and drop the ball. The dropped ball should hit the inside edge of the golf ball to the heel of the putter.