1.   The closer you are to the surface of the green, the better you'll see its contours. So squat! Get behind your ball a ways, squat down and take in the slopes of the green.

2.   Take a look at the putt from the side, preferably the low side (if there is a low side). This gives you an alternate view, but also helps you see the distance and guage speed.

3.   Look at the putt from the opposite side of the flagstick, for a third view. But a word of advice: Don't hold up play. Cut the routine short if players are waiting in the fairway.

4.   Pay attention to your partners' putts or chips toward the hole. As Yogi Berra once said, "You can observe a lot just by watching." Especially if one of your partners has a putt that is on a line similar to yours.

5.   Ask for help. Seriously - unless you're playing for money or ego, your partners should be happy to help. That's why the pros use caddies - so they have another pair of eyes to help them around the course.

6.   Pay attention to the results! The ball is a golfer's best teacher. Watch how it moves on and reacts to the green. If you misread a green, think about what you did wrong and try to learn from it.

Tips:
Reading a break and reading the speed are two different factors that combined amount to "reading a green." Practicing speed is much easier than practicing breaks.
Always take a few putts on the practice green. This will give you an idea of the speed of the greens, and sometimes gives you some insight into how the course's greens are designed.