The long putt in golf can be intimidating even to low-handicap golfers. Trying to sink a putt of 25 feet or more is difficult, but proper setup and approach will help you get it to drop.
Get behind your ball and read the green. If you are putting from more than 25 feet, it would be fairly unusual for your putt to be a straight shot at the hole. Determine where the ball will veer right or left. For a two-level green, you will have to knock the ball up a hill and the break might come after that. Figure out the breaks, twists and turns before you step up to your putt.
Lessen your knee bend and stand fairly erect when you are facing a longer putt. In order to give yourself a chance to hit the longer putt, you need to be able to swing your arms straight and easy. To do this, you need to stand relatively straight.
Hold the club a bit firmer on a long putt than you normally would, but not so tight you can't make adjustments. You grip should be about the equivalent of a firm handshake.
Use a pendulum swing, meaning you'll bring the club back the same distance you bring it forward. This will lead to a nice, smooth ball roll.
Don't take more than one practice swing when you set up for a putt--including the long ones. Once you have read the green and figured out the breaks, you'll know how you want to swing.
Tips & Warnings
Walk up to the ball and picture a 5-foot circle around the flagstick. Try to get the ball into the circle.