It's also the best way to get going again. Instead of pushing off with your toes, try this:

While you're straddling the bike and waiting for the light to turn, pull one of the pedals up to the 2 o'clock position with your toe. Now put your foot on it. When the light turns, just stand on the pedal. The bike moves forward because you've just given it a half rotation of the cranks, and you sit on the saddle, and you're on your way.

Easy peasy.