Regardless of your handicap, 70% of your putts during a round will come from inside 10 feet.
For this reason, 70% of your practice and pre-round warm up should be spent perfecting 3, 6 and 9 foot putts.
The length of your stroke determines the length of the putt. The backstroke ends at the big toe of your rear foot. The forward stroke ends at the outside of your forward foot.
To practice this, place a ball 3, 6 and 9 feet from the fringe not the hole. For the 3 foot putt, the width of your stance should be approximately the width of putterhead. For the 6 foot putt, the width of your stance should be approximately the width of 2 putterheads. And for the 9 foot putt, the width of your stance should be approximately the width of 3 putterheads.
The goal is to roll the ball to the fringe. If it comes up short then widen your stance. Fight the urge to make your stroke faster or putt harder. If the ball jumps the fringe then make your stance more narrow. Fight the urge to make your stroke slower or putt softer. It's the width of your stance.
Once you have successfully rolled the ball to the fringe move on to the 3, 6 and 9 drill. It's Putting Tip #37.