If you don't worry about anything else in your putting stroke, lock down these two fundamentals, and you'll improve right away. First, make sure the putter grip is in line with your right forearm, not hanging below it (inset). This helps the putter swing easily on the right swing plane. Second, set your hands so the grip runs through the lifelines of your palms and you're holding the handle mostly with your fingertips (left). If you were tossing a penny, you wouldn't set it in your open palm; you'd hold it in your fingertips, for feel. That's what you want when you're putting.
Keep Your Read Fresh
You want to preserve the instinctive connection between your brain's ability to judge spatial relationships and the putting stroke. I recently played a round with a 10-handicapper who had a good short game, but he went through a PGA Tour-caliber green-reading routine, then froze over the putt in his address position for almost a full minute before he pulled the club back. His stroke was actually pretty good, but he wasn't getting the kind of results he should have.An unfocused, drawn-out routine like that robs you of some fantastic built-in skill you already have. Once you make your read and get a feel for the distance, the moment you look away from your target and get into your putting setup that visualization starts to deteriorate. After 30 seconds, you've essentially "forgotten" all of the read information you acquired. Your goal should be to spend no more than 20 seconds between your final read and starting your stroke.