|I will repeat previous advice.
Learn to do suicide dives on trampolines, as well as rolling. Trampolines are a great way to hit the ground without the pain. Also, a tumbling mat would be perfect for learning on.
Never stiff arm the ground. Try to tuck your head and your shoulder..and roll with the fall (if you can). If you cannot, just make sure to always have your elbows bent. You never want to fall into the ground with your elbows locked, and your arms straight out in front of you.
New advice : If you are rolling downhill, outside on regular roads &/or pavement, use softer wheels. They will roll over obstacles a LOT better than your vert wheels!!