Make sure to include a column for each of the following: description of work or services, date worked, quantity, rate, hours worked and subtotal. This makes it easy to tally up the total when you list out multiple projects or tasks you've completed for the client.
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.