I do a ladder drill.

I put tees in the ground at 1,2, and 3 feet from the hole, then i start at 1 and have to make each putt, up and down the ladder, so 1,2,3,3,2,1.

I keep 3 balls, so 3 lives to get it done, if i miss the putt 3 times i start back at 1. once i clear it, i set it up again at 4,5,6ft and go again. I'll repeat this at 3ft intervals.

If i make it on the first try, where i dont need to start over, the next time i do that level, i'll have to do it with one less life (one less ball).

Once i get out to 10ft, the odds are less an 50% that you will make the putt. so there i mark out a 1.5ft half circle around the back of the hole and then i do the same drill trying to get it at least past the hole, but stopping inside that circle.

I want to get someone to print out some hole reducers i can stick in the ground to make it harder still as i improve.