I think the best thing I've seen in this thread so far, is to roll when you hit the ground. I know, it sounds easier than it is. I've crashed into boulders, poles, holes, other bikes...slid out of control and crashed on pebbles, wet leaves, snow and ice and was never more than scraped up a bit. The rolling your body to a stop, or into control, worked equally well for down hill skiing back when we could afford to go.
The one time I tangled with a car and lost, I went down so fast that I only had time for one partial thought and then one complete one. When the car made contact I though "what the heck i.."at which point I was thinking "I made it through alive, where is my brand new bike?". I probably would have instinctively rolled if I hadn't been thrown into the darn light pole. No broken bones, no bleeding, lotsa pain.
Yeh, learn to be at piece rolling on the ground and then try like the dickens not to crash.