This one is for the patient and dedicated. It is a great, simple, way of keeping on top of your putting stroke. It will be tedious but give it a go and stick at it.
Place a tee 9 feet (3 putter lengths) away from the hole on a fairly straight putt. Hit 100 putts from this mark using your full routine and record how many you hole.
If you do this drill weekly, you will start to see your confidence and feel on the putting green increase.
It gives great opportunity to make adjustments to your putting technique and by recording the results, you can track progress and try to beat yourself each time.