The only time I have ever fallen has been playing bike polo, so the speed tends to be fairly low and I can usually land on my feet. So my falling experience may not be salient here. But, I would say, the softest falls I have had involved catching myself with my hands ... but I feel like that is terrible advice because if you take a really hard fall, you'll probably break your wrists. I guess my advice from my personal experience is try and land on your feet and let your bike go flying. Somehow I manage to land on my feet a lot.