In terms of scoring, putting is the most important part of the game. To be a good putter takes a good technique, concentration and lots of practice. Many players lack confidence in putting. In some cases they actually fear this part of the game taking away all the enjoyment. Positive thinking certainly helps your confidence but good technique and a lot of practice is a must. You'd be surprised how confident you can get when you know what you are doing.
The reverse overlap grip is the most common grip. In the address it is best to line up your feet and shoulders as squarely as possible keeping your head over the ball. The ball should be positioned between the left heel and the center of your stance with your hands also over the ball.
There are different techniques in putting; the most important thing is to feel the stroke in your shoulders and arms. In doing so you should subsequently avoid "flipping" your hands and wrists. Keep your head, body and knees absolutely still. The only thing that moves is the arms and shoulders.
I can give you a good putting technique but I cannot tell you how hard to hit the ball. That comes with practice. The longer the stroke or the faster the stroke the harder the ball will be hit. Three important things to remember in distance is to control your tempo, follow through at least the same distance as you take the club back and always accelerate through the ball.
This is a very positive approach to putting. Try it, you may surprise yourself.