Along with the payment terms, you can specify whether you charge a late fee for invoices paid past their due dates. Some freelancers like this option, to enforce getting paid on time. You may also want to include your tax ID number in this area for tax purposes.
Next you'll want to include your contact information: your mailing address, phone number, email address, website, etc., right underneath your business name. If you'd like to up the professionalism, create and include your own logo on the right – or left-hand side of the header.