During Flag Day, people are somehow expected to display even at least one U.S. flag in their house, car, or workplace. A flag should be displayed outside the house, it should be placed at the highest point but should not be flown during bad weather unless the flag is an all-weather. Many states give importance of this day so much that even though it is not an official federal holiday, they hold parades and some even make this day a holiday.
Most people hold programs where they raise the national flag, recite the Pledge of Allegiance, sing the National Anthem, then they either hold a parade or other events. The best way to commemorate Flag Day is to display a flag or participate in any flag raising ceremony.