Those present in uniform should render the military salute. When not in uniform, men should remove their headdress with their right hand and hold it at the left shoulder, the hand being over the heart. Aliens should stand at attention. The salute to the flag in a moving column should be rendered at the moment the flag passes. If you display the American Flag, you want to do it right.
Most people know the basic rules, and the dedicated patriot knows a bit more.
Take the quiz and find out. You might be surprised. Here's the policy of our neighboring city to the north. It deals mostly with the issue of when the flag shall be flown half-mast. List of places in Fremont with flag displays.