Apologies for resurrecting a slightly old thread, but I wanted to share my experience with clipless pedals and what I have learned in hopes that others might avoid the mistake I made.

I have been lucky enough to only fall once with clipless pedals, the first day I got them. The reason for my fall - lack of speed. At least if you're a road biker, you usually have plenty of forewarning about when you need to stop, so clip one foot out early while you still have a good bit of momentum, then stop yourself with one foot ready to brace you.

The temptation I had when starting out (and what I've seen most people try) is to go slow while still trying to figure out your new pedals. With momentum on a bike comes balance and time you need to unclip. If I could do it over again, i would get to a large, abandoned parking lot, clip in with one leg, start pedaling, clip in with the other, pedal some more, unclip one leg, apply the brakes, set one leg on the ground, unclip the other, and place both legs on the ground. Voila, you've just figured it out.

I also really like the idea others have mentioned about riding with one cleated shoe and one normal shoe while learning, but at some point you're going to have to strap that other shoe on, so remember, keep that speed up and you'll be fine.

Hope that helps.