A friend of mine recommends picking the foot that you stop on (i.e. usually put down one foot or the other at lights) and putting the clipless pedal (which you clip into, I assume you know the confusing semantics) on the other pedal only for a few weeks. Get used to clipping in/out on the one leg before adding the second.
Also, go to a big parking lot and ride around in circles doing practice quick stop scenarios.
I love clipless pedals, now that I'm used to them.
I also really like my eggbeaters over my old SPDs, they are easier to get in and out of, IMHO.