I often ask my students, “if you had to teach a friend who had never played golf before how to putt, what would you tell them?”
A lot of what I hear has to do with the path of the stroke — either you want to stroke it on an arc, or straight back, straight through, or back on the inside and out past the ball — but I’m a pretty simple guy and I like to look at what the math says.
It’s easy to see when you hold your putter parallel to the ground that it travels on an arc and there is no face rotation because we’re playing on a tilted plane.