An extra-long or uneven stroke can make it very difficult to control distances on the green, regardless of the length of putt. The likely problem? An uneven stroke. Here's one way to fix it.
Find a flat 10-footer. Swing the putter back as far as you think is needed, and just as you make contact, cut the power. I call this "braking." You may feel like you're stabbing at it, but this trick matches your follow-through to the length of your backstroke. You'll have a smooth, "even" motion that properly accelerates and reaches peak velocity just prior to impact — the keys to deadly-accurate distance control.
Tip: If you leave putts short at first, lengthen your backstroke (while still braking). Using the 10-footer as a foundation, you'll soon build a repertoire of strokes, and you'll be rolling 'em in from every distance.