I haven't fallen (yet!!) but here's what's helped me.
I grew up in Wisconsin, so I skiied. Alot.
To stop, as a beginner, you're taught to "snowplow"- kick both heels out so your feet make a wedge or a "v".
When I was in the shop trying to #$%^$#!! get into these pedals (time somethings with spd cleats) on my brand new Giant bike (xs size, which I find ironic) the LBS guys and I couldn't figure out why I wasn't "clicking into " the shoe. Then one said treat it like a ski boot and- wahla!- i'm in! So it was instinct that if I wanted to stop to turn my heels out and then my shoes pop out.

I think I've just lucked out.

BTW, I"m getting my Trek 7.1 fx next week. Can't decide on clipless pedals for that one! Any suggestions after reading all this would be great..