This video discusses a number good point about how to choose a golf putter.
It's important to remember that finding a putter is about finding something that works with your putting stroke. There is a lot of debate about what comes first -- the putter or the stroke -- but we think it's the stroke. That being said, you want to first find a putter that looks good to your eye. There are a bunch of different putter styles so the best thing to do is go with your instinct. What looks nice? What inspires confidence?
Once you've selected a style, take the putter outside onto the putting green. You're looking for a good fit. Remember that a putter can be customized to fit your body and swing type. You should now be looking to see if the lie is flat on the ground. If the putter is too upright for your stance, the heel will be in the air. If the putter is too flat, the toe will be in the air. You want the putter to lie flat on the ground -- otherwise you'll have a tendency to push or pull your putts.
Next you want to consider the length of the putter. Taking your normal stance, does the putter sit on the green or is it short? If you're finding yourself gripping down on the putter or if you feel like your stretching to hit the green, you're going to want to get this changed. A new putter shaft is a very simple process for a local pro shop. You'll also want to find a grip that suites your preferences.