
When I am walking up the fairway approaching the green I look for the lowest part on the green, and Then I know generally which direction the ball is going to want to move towards. Then I go behind the ball and look even closer to see how severe the break is and approximately how much break I should play it. The break of the green varies from each course do to the speed of the greens. The faster the greens are the more break there will be, the slower the less break.
I along with many other golfers go into a squatting position behind the ball, to determine the break of the green, the only reason why people do this is because the lower to the ground the easier it is to determine the break. Reading greens takes some practice, but the basics are the slant of the green determines where the ball will tend to go.