Find your own tempo, for it varies with the nature of the person, and learn to hit the ball with a rhythmic stroke. Move the putterhead through the ball, not just to the ball. Accelerate through the impact area. Make contact the ball authoritatively and you can get the ball rolling with the right speed for any given putt. Practice for a long time to get the putter to go back and through the same distance.
Knowledge accumulates with experience.
Play all different types of greens and practice long putts day after day to help your distance judgment. Spend as much time on the greens as on the range hitting balls.