A taut string stretched directly over your target line gives continuous visual feedback on whether the ball is actually rolling on-line.
intermediate15-20 putts per session, twice a weekString line (or string plus stakes)4+ tees
How to perform it
1.Stretch a string tightly along the intended putt line, from ball to hole, or along a straight practice line.
2.Set a small tee gate around your putter head for path feedback.
3.Set a second small gate just ahead of the ball to check your initial start line.
4.Roll putts along the string, checking that the ball tracks directly beneath it without drifting.
What you should learn
•To separate a bad read from a bad stroke — the string removes any ambiguity about the actual line.
•What a truly square start line looks like compared to what you assumed it looked like.
After a few weeks of practice
You'll start putts on your intended line far more consistently, and you'll be able to tell immediately whether a miss was a read error or a stroke error.