Putting technique seems to be the most diverse. Sure there are also all kinds of different swings, if you look at the long game. But whenever I am playing golf I often meet or see somebody taking an approach to putting that I have not seen before. Well, whatever works I think to myself then.
But I also believe that there are fundamentals to putting that should not be messed with. Like there are with the full swing. One of those fundamentals is the setup. In no other part of the game you are as close to the ball and the target line as you are when you are putting.
In fact you should be over the ball looking down on it. The ball should sit perpendicular under your left eye. The easiest way to learn to position yourself the exact same way each time you want to putt is with the help of a small mirror. Get a mirror of approximately 12 by 18 inches. A mirror tile will do, too.
Then use masking tape and place a strip lengthwise on the reflective side of the mirror. Place a second shorter strip perpendicular to the first one, a little more to the left side on the mirror. You should now have a small cross on the mirror.
Place that mirror on the floor and take your normal putting setup. Leave the golf balls aside for now. Actually imagine the golf ball sitting at the intersection of the cross you made with your masking tape. When you get into your address position, your putter should line up with the cross section of the tape. The reflection of your eyes should be on the lengthwise tape which represents your target line. Your left eye should be above your imaginary ball.
Now practice your putting setup with your new training device. You can take the mirror also with you to the practice tee, if you want to. If you practice your setup with the mirror a couple of minutes for some days, it should become second nature to you which is when your putting will become more consistent.