Unclip at the bottom of your stroke, and just let your unclipped leg hang straight down, also put your clipped in side down. Coast up to crosswalk and as you brake to a stop ,slide your butt forward and step to the ground with your unclipped foot. After you are sure of your footing raise your clipped foot to a "ready to go" position. When it is safe to proceed (not neccesarily automatically when the light turns green) stand on your clipped in pedal and get your butt on the seat as you coast forward, clip in your loose foot at the top of its stroke. If you miss ,no big deal just pull the crank around with your clipped in foot and try again. I have seen plenty of people go over with the high and resting unclipped position, never with the loose and hanging unclipped position. Its how all the cool kids do it in my neighborhood anyway.