How do you figure out the wind?  Because of trees and terrain, the wind will not always go in one direction on a golf course.  There will be a prevailing wind, but on some holes it may swirl and even appear as going in an opposite direction.  Throwing grass into the air does not help much, as it only tells what the wind is doing near you.  Look at the tops of the trees, the flagstick, and water in ponds and lakes to see the direction of the waves.  Watch your fellow golfer’s shots to see how the ball is being affected by the wind as it flies.