Below the total you can include any additional information, such as a thank you or a reminder. - When you work out the contract with each client (and yes, you should have a contract in place!), you'll list out the terms of how often you plan to invoice and when you should be paid. For instance, you can agree to bill on the first of each month, or biweekly so you get paid every other Friday.
Next, you need to specify your payment options — whether you prefer to be paid with cash, a check, a credit card or a service like PayPal. Some companies will offer direct deposit, if you do regular work for them, but more than likely you'll have to send an invoice to request payment every time you complete a project.