These are the two most important elements of putting.

It is essential to remember the longer the putt is the focus more on the speed and less on the line.  If you misjudge the line but have reasonable speed you will start to eliminate three putting.  Imagine a wide path to the hole with maximum break.  The speed is critical and approaching your long putts using this ideal will give you a better opportunity to make the second putt.  On the long putts your goal is to put the ball within tap in range, and that means distance control.

On short putts, focus less on the speed and more on the line and aim.

Whether it is a long or short put the length of your backswing will determine how fast the putter will move and therefore how far the ball will roll.  You are trying to create a pendulum which is an uninterrupted motion.  Control the speed with your backswing length.