It can be easy to take tree stand safety too lightly, but this is a very costly mistake. Statistics show that thirty percent of hunters using tree stands eventually get hurt. Every year we all hear of people getting hurt from falling out of tree stands. I even know a couple of them personally. My father broke his ankle, and a friend broke his back. Just this year, a hunter in Ohio was missing for two days. He was found hanging from a tree by his chest harness. 

Chest or waist harnesses alone are not really safe at all. You should always use a safety harness that attaches around your chest and under your legs. Seat of The Pants makes a good harness. Other companies make vests with the harness built into the vest. 

Another good safety precaution is to carry a knife in an easily accessible place on yourself in case you need to get to it in a hurry. In an extreme scenario, you could fall from a tree and be caught hanging. You may be unable to get into a safe position, and, even worse, you could possibly suffocate in this position. In this case, cutting the safety rope with you knife and falling might be your best option.