Square is the name of the game in putting.
If at address you’re square, but then take the club too inside or too outside, you will need to manipulate the putterface to get it back to square through impact.
SHORT PUTTS: Straight back and straight through are key on short putts. LONG PUTTS: For longer putts, the club will naturally move to the inside slightly. This is simply because your shoulders are more active with longer putts.
Beware of taking the putterhead outside the target line. If your putts are consistently missing left, this may be the culprit.