I like what I call the touch drill. It forces the player to focus on speed and results in better touch on the greens for all length putts.
Take some colored tees, quarters, dimes and pennies for clear distinction and create a small grid some three feet apart. Space the items, say the white tees (one on the left and the other on the right about the three feet apart. Then take the next set of items, say the quarters and do the same thing about a foot back from the tees. Do the other small items the same way until you have a grid of about four or five spaces with imaginary lines between the objects. Then, place a ball you’ll be putting about five feet away from the first line on the grid and put to it. Try to get the ball to stop just past the first line (of sight between the two matching objects) but short of the second line. Then, bring the ball back to the original spot and do it again, this time trying to stop the ball just past the second line but short of the third. Do this until you complete the drill. I place the grid just in front of a hole on the putting green so when I complete the grid successfully my last putt is to go through the drill and into the hole.
One important element that forces me to focus and be successful on the speed is: If I were to pass the line I’m shooting for and the ball ends up too far into the next grid or beyond, I start the drill over again. If I miss the putt into the hole as my final test after completing the drill, I start over again. I don’t penalize myself for being short on any putt and allow myself more tries to get it right without starting the drill over again. You’re bound to have better touch after working on this touch drill and will surely become a better putter.