Golfers begin to putt badly when they start getting too concerned about their putting stroke or putting mechanics. Having a good putting stroke is substantial so take the time to learn one and train the mechanics regularly.
Putting is a major part of the game of golf. It accounts for almost half of the shots in a round of golf, yet, most people don't practice this part of their games.
Here is a couple of great golf putting videos...
Golf Tips: Putting to a Tee
Golf Tips: Putting to a Tee
Here is another golf putting tip
golf putting tip
this exercise will help improve your distance control when putting