In the beginning, you may use a lot of free tools because you don’t have the money to pay for them. There’s the free invoicing apps and email newsletter services for small businesses. You might even go old-school and track expenses in a spreadsheet.
The problem with these is that at some point, you’ll find yourself spending more time managing them. It’s not exactly wasted time, but it’s not revenue-generating time for your freelance business. When you hit that point, it’s time to consider investing in a few tools, apps, or services that’ll give you back your time and let you focus on what you do best: write.