Could one conceivably prepare for one's first time clipping in like this?: Ride your favorite trail, count the number of times you have to dab (put your foot down), and then know that the first time you ride the trail clipless, you'll fall down at least that many times? Or is that too pessimistic?
No, this doesn't work. Your clipless pedals will help you clear sections you previously had troubles with, as you know that, "Heck, my feet aren't coming out of these dern contraptions, so I better make that technical climb, or I'm gonna die!". Then you fall over when you hit a pebble!
L8R
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"Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming, "WOW, What a Ride!" - unknown
"Your Bike Sucks" - Sky Yaeger