This is an acquired skill in golf. But, everyone can learn this skill. There are a few elements to consider when reading a green.

Slope

The golf ball obeys the laws of gravity. On a side hill slope the ball with always turn towards the lowest point. Going downhill the ball will run further than a ball going uphill using the same length of stroke.

Green Speed

Speed of the greens is dictated by the amount of friction between the ball and the grass. Different grasses cut at the same height can create different speeds because amount of friction each type of grass creates with the golf ball. Pay attention to the species of grass and the height it is cut.The stimpmeter caluclation is the amount a ball rolls after being rolled down a stimpmeter. The higher the stimpmeter reading the faster the greens.

Weather

Wet weather will slow down the greens and the ball will run straighter. Dry weather increases green speed. Windy weather can create unique influences. Wind can slow a putt going into a headwind but create more break, increase speed going downwind but lessen break, or increase the amount of break going crosswind.

Grain

Grain is basically defined as the direction the grass is leaning. The grain dictates the amount of resistance placed on the ball as it rolls. Grain influences the putt similar to wind on a gusty day. Speed will increase going down grain but the amount of break will lessen. Speed will decrease going into the grain but increase the amount of break. Cross grain the ball will tend to break more. The sheen or color of the grass can tell you the direction the grass is growing. A light color indicates the grain is with you (putting down grain). A darker color indicates the grain is against you.