I think your landing strategy has to be pre-programmed. Practice falling a lot! Otherwise, just do your best to NOT stick a hand out.
The incident that first got me to wear a helmet was this: For background, at the time I was coaching HS diving. I was riding my OLD 10-speed and caught my front wheel. As I was going down, I planted a foot and ended up doing a somersault. I landed on my feet, facing back the way I'd come, and as the bike came down I caught it by the top tube. I stood there for a second waiting for the "TA-DAH!" to sound, and for the judges' scores. Then I realized how lucky I'd been. The only damage was the stem being a little crooked.