There are three elements to the skill of putting. Firstly, you must be able to master a consistent ball strike to get the ball rolling online, next you must learn about pace and how hard to hit the ball and finally you must learn how to read greens so you know where to aim the ball.

Consistent Ball Strike

The fundamentals of a consistent, repeating golf stroke is that you must work on creating a stroke that does not involve the wrists moving. The stroke should be created by a rocking of the shoulders so that your arms act like a pendulum. This will allow you to be more consistent in your putting as there will be less moving parts.

How hard to Hit the Ball

Also to hit the golf ball further, your "pendulum" swing should be longer on the back swing rather than a faster or more forceful hit. For all lengths of putts, the tempo of stroke should be the same and just the length of backswing should change as distance requirement increases.

Reading the Green

Finally, reading greens is important so that you can work out where to direct your putt. This really can only be learnt by practice and it's more crucial on longer putts. Sometimes on shorter putts a little extra pace can reduce the need to read a break. Also with uphill putts you can be quite aggressive and this will keep the ball on-line but for downhill putts you need to be conservative and hit the ball much less aggressively. Therefore reading breaks on the latter is vital.

There is no right or wrong putter for you. Find one that feels good in your hands and is the right weight for you. Also check the shaft length and you may find shorter than standard helps. Finally make sure you feel comfortable lining up your putts with it, some people find they can aim better with certain putters.