Track your time each step of the way – Time is money, so it's vital to keep track of it. It will also help you learn how long it will take to complete similar future projects. This will facilitate a better work schedule so you can tackle more jobs. Accurate time tracking will add more transparency to your billing and will help clients know what to expect when they need you to work on similar tasks later. Use time-tracking mobile apps so you can clock in and clock out right there on the job and not have to estimate your work hours once you're done.
A professional header: The first item on your freelance invoice should be your business name, or your full name, in professional (and easy to read) font. The font size should be a little bigger than the rest of the text on the invoice, and possibly even bolded for emphasis. Next you'll want to include your contact information: your mailing address, phone number, email address, website, etc., right underneath your business name.