Summarize this article:

Right before you fall, bend your knees for the impact and land on the balls of your feet. This reduces the impact on your body and can be the difference between surviving with minimal injury and permanent damage to your spine or pelvis. After your head, your pelvis is the other body part you want to avoid injuring during a fall. The pelvis is a ringlike structure of three bones located at the base of the spine. It's surrounded by blood vessels, nerves, and organs, so an injury there can cause substantial damage, including paralysis. Do not bend your knees too far. You only want a slight bend so your knees aren't locked. You want to land softly on the balls of your feet. This will cause you to slightly lift up, resulting in less shock to your body and will add power to your spring. Your legs will sustain less injury so hopefully you don't break any bones or severely damage your ligaments. You should position your body to roll forward after impact, rather than immediately bounce up or collapse. Tighten your stomach muscles to draw your knees towards your chest, tuck your chin in, and remember to keep your arms in as you prepare to roll. Once you have tucked your body into a ball, roll at a 45 degree angle onto your shoulder instead of straight forward or sideways. Roll onto your back and if you don't feel any pain, continue to roll back onto your knees and then your feet. Rolling forward allows most of the energy from your fall to release into the roll, and not into your legs or spine. If, once you have rolled onto your shoulder, you think you may have broken a bone or injured your spine, do not move onto your feet or knees. Stay in a comfortable position until help arrives. Make sure to avoid any impact on your head or neck when rolling.

Summary:
Bend your knees. Extend your knees after you hit the ground. Tuck your body. Roll forward.