I never unclip both feet while I'm still moving. That makes the bike unstable and more difficult to stop. Put one foot on the ground before you unclip the other one.

Also, don't unclip both feet when you're stopped at a red light or a stop sign. Clipping in both feet takes more than twice as long as clipping in one foot. You usually want to clear the intersection quickly and an extra slow start is not helpful. Learn to stop on your clipped-in pedal so you can get an extra fast start when you need to.