Practice putts over a chalk line on a flat spot
For grooving your putting, the instructor's most important rule is to lay down a chalk line (or anything straight) on a flat area as a reference for the ball to roll over. He also puts a mark on his ball and lines it up to that reference the exact same way every single time.
Channel: Bryson DeChambeau
Watch official source at 0:49Why this context matters
Framed as "step one" of a basic intro to putting.