How do you aim a long breaking putt? Well, you have a few options. Dave Stockton and Arnold Palmer have advised me over the years to pick a spot right in front of the ball on the path to the putt's apex, or highest point of the break. Another strategy is to aim farther down the line, about halfway, at the actual apex.
My preferred method is a little different. First, I figure out how much the putt will break. Then, I pick a spot that's an extension of that path to the apex, all the way out to hole-high (above). This allows me to treat a big breaker like it's a straight putt. I simply aim at that spot even with the hole.
Average golfers tend to underplay break, because their focus is typically on the hole and not on getting the ball on the correct path. These options move the emphasis away from the cup and help you start the ball on a line that gives it a chance to drop.
One of the benefits to walking when you play is seeing the contours of a green as you approach it. That's where you should start your read. Then confirm what you see by walking outside your putting line to the cup, feeling the slope with your feet.
Excerpted from the DVD "Lessons of a Lifetime II," by Tom Watson.