The fundamental rule of flag etiquette is to treat all flags with respect and common sense.
The Stars and Stripes takes precedence over all other flags when flown within the United States. It should not be flown lower than another flag nor should it be smaller than another flag flown with it.
Other flags may, however, be flown at the same height and in the same size. Other national flags should not be smaller nor flown lower that the Stars and Stripes when displayed together. If it is not possible to display two or more national flags at the same height, it is not proper to display them together at all.
The point of honor is on the extreme left from the standpoint of the observer (“the flag’s right”). The order from the left to right of flags flown together is: the Stars and Stripes, other national flags in alphabetical order, state flags, county and city flags, organizational flags, personal flags. If one flag is at half-staff in the morning, other flags flown with it should be at half-staff. First raise the flags to their peak, then lower them to half-staff. The Stars and Stripes is raised first and lowered last. A salute (hand over heart for those not in uniform) should be rendered when the flag is raised, lowered, or carried by on parade; when the Pledge of Allegiance is recited; and when the national anthem is played (unless flag is not present).
It is proper to fly Stars and Stripes at night, but only if spot-lit. No flag should be flown during weather which might damage it, based on common sense interpretation of circumstance.
When a flag is no longer of dignified appearance and cannot be repaired, take it to a veterans group or organization for disposal. If no group available, it should be destroyed in a dignified way (burned or sealed in a bag or box before being sent out for trash collection).
In a public gathering (lecture hall, church, etc.), the Stars and Stripes should be to the right of the speakers or on the wall behind them.
Then canton of the flag (the blue “field” with the 50 stars) should always be to the observer’s left except: when displayed on a casket; when displayed as a decal on the right side of a vehicle (bus, truck, plane, etc.); when worn as a patch on the arm ( but use on the left arm is preferable).
The Stars and Stripes should be in the center of a group of flags only when: the center pole is taller than the others or when a fan-like arrangement makes a center pole higher than the others.
It is not illegal or improper to fly any flag (state, ethnic group, organization, etc.) alone, but it is always preferable to display the Stars and Stripes at the same time.