Maelstrom's got it: nothing is better at making you better at coming out of crashes unscathed than practice! You don't want to think about falling, you want your body to do the right things. Sometimes, you'll have space and momentum for rolling. Sometimes, slapping out can really help (esp with padded gloves). And sometimes you get lucky and fly off your bike, land on your feet and watch your bike tumble by. But mostly it hurts a bit and you move on.