I've always been a streaky putter- the type who has the ability to read a 40 foot triple breaker and the touch to cozy it up there, but the same guy who can lip out 3 3 footers in a row.
Lately, I've been focusing on two specific aspects of my putting stroke- 1) aim, alignment, posture and 2) touch. Sounds like that pretty much covers all of putting, huh?
Careful analysis of my grip and set up revealed why I had a tendency to stub putts (grazing the grass) and leave them right lately- too much shoulder tilt away from the target, and a grip that required some contortion to get the forearms level. I agree with Pat O'brien's philosophy that the shoulders should be LEVEL when putting. I've been running into the same problem in my pitching and chipping- too much axis tilt away from the target.
From this, I've extracted two very basic fundamentals
1) level shoulders
2) level forearms
Note how little shoulder tilt Vaughn Taylor has with his putter set up
compared to Phil Mickelson's (best wishes to the Mrs) full swing set-up
I made some set up changes (grip, ball position, shoulder level) and found that my stroke was much freer and more athletic. Setting up correctly, I could simply direct the putter squarely at the back of ball, thinking only of how far I wanted the ball to roll. In order to keep my mind free of mechanical thoughts, I've been using a drill Nick Faldo used to use, described here.
The important parts are quoted below:
"Now, feel the corner of your lower thumb on the grip that is closest to the target. On your right hand (for right handers) it will be the corner of the nail on the outside of your thumb. Take some practice strokes feeling that corner pointing at your target at the end of the motion. Now execute some three to six-foot putts making sure to hold the point at the ﬁnish of the stroke.
By doing this you will discover that the ball goes the direction you pointed good or bad. Two things will come from this drill: (1) your focus will shift away from the putter head and ball; and (2) you will complete your stroke, giving you better rhythm and distance control."
This drill worked wonders for me, helping me trust my stroke as well taking any "hit" out of my motion.
For more putting tips, I suggest checking out Pat O'brien's site as well as Geoff Mangum's.
Pat's site has some other information about his ideas on how set up influences the stroke (which I agree very strongly with), and Geoff's site has a lot more technical information on how to develop touch and green reading ability. If you can sort through all the technical talk, Geoff has some great imagery than can help you visualize your putts better- which essentially means, he can help you PUTT better.
Since my goal as an aspiring professional is to someday be "putt[ing] for dough", both these sites are money in the bank.