The problem: Most of your putts finish way left of the hole.
The solution: If your setup and aim are solid but you consistently leave putts left of the hole, the problem may be with your finish -- namely, you open your shoulders to the target through impact in an effort to track the ball to the hole.
How to do it: The key is to track the ball with your head rather than your body. To do this, let your putter move past impact ahead of your eyes, rather than trying to keep your eyes locked on the ball as it leaves the face. This may feel odd at first, but it will allow the putter to complete its movement through the impact zone while your shoulders are still square to the target line, resulting in a putt that will roll exactly where you aimed it.