I have been using clipless for two years now and haven't fallen yet, though I have had a few close calls. I consider myself a moderately coordinated individual and I haven't had much trouble. If you have difficulty releasing, don't panic and try the other pedal. Engaging the first time comes with practice. I still don't locked on the first try all the time. I try to plan ahead. I usually ride the same paths around town and there are some intersections that are on a slight incline. I will stop in a higher gear than norma so it will be easier to start if I miss the first time.
Remember to tighten the cleat before each ride and keep the pedal clean.