Using an elevated swing, it is easy to develop good feel for aiming properly and working on good eye positions over the ball. It is a great way to develop some very effective fundamentals for putting.
In this video, PGA Professional Todd Kolb explains how to use the elevated string and how it can be beneficial to any golfers game.
It is important to find a fairly straight putt. This can be done simply by rolling golf balls towards the hole from different angles. After this is done, place the string behind the hole and behind the location of the ball using stakes, about 10 feet away from the ball. The string would ideally be elevated 3-4 inches off the ground.
Todd points out in the video that the ball should be placed under the string to the point where the ball is almost split in half visually by the string, directly below the string. After this is done, there are a number of things to work on with the elevated string such as eye line, stroke arch and proper alignment to the hole.
After working on this, it will become easier to gain consistency and understand how to use some proper fundamentals with putting.