Wanna be a good putter? Here are some basic fundamentals you should be practicing.

• Get a putter with a very distinct line marked on it to indicate the target line and practice with a chalk line. You can get a chalk line at any hardware store for 5 or 6 bucks, and it's as valuable a training aid as there is anywhere. Find a putt on the practice green that is straight. Snap a chalk line down from about 5 or 6 feet to the middle of the cup. Make sure that the entire length of the line on your putter is exactly on the chalk line. Start making putts. This will train your eyes to "see square" precisely.
  
  
• Keep your the pressure in your hands soft and constant throughout the stroke. Sensitivity is obviously a huge part of putting. If your hands are tight on the grip you are diminishing your sensitivity - period. Also, if your grip pressure changes during the stroke, it's probably not "a stroke" but more likely a jab, flinch, spasm, push, hit ... well, you get the point -- good luck with that kind of technique.
  
  
• There is no independent action in the hands. Nothing could be more logical: If you do indeed have the putter face aligned precisely, as in the first point above, the last thing you'd want to do is to change the position of the face. Therefore, your hands should not be moving independently of your arms and shoulders. To see if your hands are moving, as a drill try watching your hands very carefully (instead of the ball) a few times. You'll see what your hands are doing quite easily.

There are many more (seemingly endless) details about putting, of course, but if you turn these fundamental concepts into habits it will take you a long way toward being a consistently good putter.