Start by positioning each of the coloured 'Putting Gates' at specific distance from the ball and across your chosen target line. This will create a specific putter face angle of error that you will need to achieve to successfully putt the ball through each gate.
For example on a straight 10ft putt, you will need to develop accuracy of less than 1 degree of face error in your starting line to be successful, at 20ft you need less than 0.5 degree. The RED gate will need to be set-up at a distance of 20" the SILVER gate at 14" and the BLACK gate at 8"
The goal is to roll your putt through each gate and not to make contact with either side. If you make contact with the gate, you will get instant feedback if your putter face has a greater error than 1 degree in its angle at the critical point of impact.
If your putt ball makes contact with the right side of the gate then your putter face was OPEN. If you make contact with the left side of the gate then your putter face was CLOSED.
You want the putter face to be consistently square at impact as this will allow the putt ball to make no contact with the gates and help to train and develop the skill of starting your ball on your chosen line.