Speed is king on the greens
You can chop tons of strokes off your score—right away—if you fine-tune your putting speed. On any putt longer than 15 feet, speed is more important than direction. Look at it this way: If you get the speed right, you can be off by a good two feet on your read and still have an easy putt left. Set up a circle on the practice green (using string, tees or a training aid like the Lag Ring I'm using here) six feet in diameter, with a hole in the middle. Once you can consistently lag putts into that circle, you'll never have more than a three-footer for your next putt. Trim some of those three-putts and your score will be in the 90s in no time.