Configuring these fields before creating sites is best practice.
By marking the fields as mandatory, users who have the permission to create new sites will not be able to finish creating the site without filling these fields.
Unique ID: Require the user to enter a Unique ID when entering a site.
First Name: The main contact's first name.
Last Name: The last of the main site contact
Job Title: The job title of the main site contact.
Phone (Main): The main phone number of the main contact person.
Phone (Other): Secondary phone number of the main site contact.
Fax: The contact's fax number.
Address: First line of the company address.
Address Line 2: The second line of the main company address.
City: Company city
State: State or province where the company is located.
Zip code: The zip or postal code of the company.
Country: Country where the company is located.