I've already posted about lag putting and how I simply avoid looking at the ball to help control distance on long putts (more so as a drill than during play). But in reality, there's more to it than that. After all, one wants to roll it close, so there's always a marriage of distance and line.
I've noticed that if I'm not paying attention, my right hand becomes overly active in all my golf shots--including my putts. This can cause the left wrist to break down and flip. One often hears the analogy that putting is like rolling a ball toward the hole; many pros (like Jackie Burke) favor an active right hand with a passive left hand, while Dave Stockton likes the left hand/wrist and arm leading (with a forward leaning shaft with the left wrist tracking right down the line). This is often called the "forward press." However, a forward press can cause problems depending on the style of putter (see below on putter style) and the lie of the putter on the ground. In other words, pressing too much can cause hitting down on the ball and applying backspin, which will cause the ball to hop at impact and then stop well short of the target. Instead, I focus on keeping my wrists and hands out of the motion, with my arms and club forming a firm Y shape, so that only my shoulder motion transfers energy into the ball. My left wrist is straight (slight forward press) but unmoving, and my right wrist is bent more but still unmoving. The longer the putt, the less grip pressure I use, such that the weight of the club head is utilized to transfer maximum energy into the ball. The shorter the putt, the more grip pressure, because this makes for a more accurate putt that stays on its line.
But as important as the forward press is, it's also crucial to keep the hands unified during the putt (as if the hands were melted together). The closer the palms can be to each other (mirroring each other in a "praying hands" style), the better the putt will be. This is why a reverse-overlap grip with the putter running through the lifeline of the palm is also important. Another way to think of it is that the forearms should be on the same plane, facing each other (i.e., the right forearm should not extend above the left forearm at address) and forming a Y shape. Then, you just rock the shoulders to move the Y back and forth. Sometimes, I tend to let the club wander from that lifeline in my palm, and this can produce too much hand action; the putt should be driven by shoulder motion only.
Also, be careful with the angle of the wrists and position of the ball relative to the head/eyes. One should be looking in at one's hands when in the address position. The ball should SEEM like it's on the inside of the eye line, but if you plum bob using your putter, you'll see that the ball is actually directly below the eyes.
I have to concentrate on NOT moving my lower body and ONLY rocking my shoulders (again, with firm wrists). If I'm not careful, I will move my lower body like in a chip shot. The legs must remain perfectly still, and the upper body should NEVER turn to face the target (even slightly). The best way to do this is to keep the head down until after the putt is away; take practice strokes focusing on keeping the lower body completely still. It's a huge mistake to look up early, as the tendency will be to unconsciously steer the putt instead of relying on the initial line and practiced motion relative to that starting line.
I have to remind myself to get the putter head close to the ball during setup, as this can also affect the spin put on the ball (ideal spin is end-over-end or topspin). Believe it or not, it's easy to slice or hook putts just like full swing shots. It's also easy to apply backspin (if you hit down, the ball will often hop and then stop well short of the hole because it checks up). It's also important for me to slightly raise the heel of the putter off the ground (toe more down), which makes the shaft more vertical and allows for more of a straight-back-and-through stroke.
The style of putter also has an effect on the address position and chosen stroke style. The putter I'm currently using is a Nike OZ-2 blade style putter, with an offset shaft. The offset is designed so that one can address the ball with the hands and eyes directly over the ball with a vertical shaft; too much forward pressing (leaning the shaft forward and locking in the left wrist in too straight a position) causes backspin with this putter. This offset makes it easy to take a neutral stroke--either arcing or straight-back-straight-through.
Finally, it's important for me to hover the putter head ever so slightly before stroking the ball. If I begin the stroke with the putter resting on the ground, I have a tendency to jerk the club either too much outside or inside, whereas hovering it allows for a pure back-and-through roll.
Though I admire the rolling analogy (because I know how to roll a ball with my right hand), I think I putt better--especially on closer putts--if I can take my right hand out of it more. I've tried cross-handed putting and the "eagle claw" putting grip, but I don't really think they help in the long run (many gimmicks like this often seem to help at first). What I'm trying now is to flatten my left wrist (and thus lean the shaft forward).
One caveat to the firms wrists: Don't be afraid to release the right hand to lag long putts closer.
Mr. [Jackie] Burke tells me out on the practice putting green. "Just let the weight of the putter make the swing and you stay the hell out of the way. Whatever speed you go back with, that's the speed you want going forward."
Hold the putter with the top hand with about a 4 pressure (on a scale of 1 to 10) and use the bottom hand to only guide it while holding it with a pressure of about 2. Make the stroke primarily with the top hand. This will prevent the wrist from breaking and also keep the putter in line during the stroke.
An amazingly simple tip that will help you get those long putts closer is just to stand taller.
Seem to easy?
The key to rolling a long putt close to the hole, or even knocking in a few of them, is to make a long, flowing stroke. And the best way to do that is to stand taller.