In my world of teaching kids golf, I can say without a doubt that, a new golfers first big leap in scoring is when they stop 5 & 6 putting and begin 2 & 3 putting. This occurs when they figure out how to hit the first putt close to the correct distance.
The two problems we have to solve in putting are distance and direction. Direction is pretty easy because the stroke is short enough to keep the face more or less square to the path. The difficult part is getting the distance close enough to get the ball in the can’t miss range. What I mean by that is that the best players in the world are 99% from 2 feet but, 50% from 8 feet and only 14% from 20 feet. So, I teach/preach “let’s get really good at making the short ones and make the long ones into short ones.”
The approach that seems to work the best is to pretend every putt is straight and flat but pick a target that makes sense. I teach our young players to simply stand behind their ball and feel the slope with their feet, then pick a target that makes sense, (if you feel the slope between you and the hole is down hill and sloping to the right, then your target will be short and left of the hole) then aim their train at that target (the ball rolls down one rail and we stand on the other) then take one last look at the target we picked and putt without delay to that target.
The goal is to create a nice scatter pattern around the hole within about 2 feet. If you get good at this then you’ll make your fair share of the long ones and leave yourself with little work for your two putt.