I remember when I first got the clipless, I was living down in Tallahassee Fl and I had just put them on the road bike that I had for a few months, down there, there is a rail trail that I would ride sometimes, since it was flat I thought that would be a good place to test the clipless for the first time...I had practised the motion of getting in and out at the bike shop I bought them from, so had that down..So I set out and did the normal ride down that trail that I did, went down to the 9 mile mark and then turned around..The first time I got down there I was telling myself, remember to clip out befor you come to a stop, well then I got to that point and I had forgotten to clip out, and so down I went, kind of in slow motion, and skined my left knee..Nobody was around, so it wasen't to bad, but I just racked it up to inexpierence and went on..Well call me crazy, but for the next 2 times that I went back to that point, I always forgot to clip out, and time and time again I crashed at the same point on the same scar that I had created the first time!!
...Finally I had crashed 3 times, each time when I got to that point, that I finally remembered to take the foot out so I wouldn't crash again, and the wound healed up!!..Never crashed again untill 3 years later on a new bike in a parking lot, but that wasen't bad, and since then, I haven't crashed because I forgot to take my foot out of the pedal....
So sorry it's soo long here, but don't feel bad if you crash a few times befor you get the hang of it, that's just normal, but as others here say and I echo, eventually it becomes habit and you don't have to think about it..
Strange thing here also, I would ride my bike with the clipless on other rides down there in florida and not crash, but for some reason, when i got to that point on the trail and had to stop, I would forget those 3 times and always crash, strange!!!
Benjamin