Having a post office box for a business or for personal use is safe and convenient. You are the only one who has a key, so there’s no danger of missing mail. Someone who moves around a lot can have a stable address that's accepted by most companies and agencies. Many businesses prefer to have a PO Box, and in some areas a PO Box is all that's available.
Ask the clerk at the post office where you have the box for the proper form to add a name to the list of people who get mail at that box. If this is a new box you are requesting, be prepared to show proper identification.
Fill in the name and physical address on an empty line on the card that's handed to you. If the box is rented under a business name, the individual names of the owners should be listed on the card.
Complete any other required information. List your actual physical address, giving the 911 emergency number assigned to your residence or business even if there is no mail receptacle at that address.