Writing
There are freelance writers who manage to pull in more than six figures every year. It takes plenty of work, but the upside to writing is that you don't need any special equipment to get started. There are plenty of sites that list freelance writing gigs that can help you land your first client today. You don't even need to be Hemingway to land these projects, you just need to be able to write clearly and avoid grammar mistakes.
Translation
If you're fluent in a second language, translation can provide an excellent opportunity for freelancing. There are some variables in how much a freelance translator can earn that can make a major difference. However, a freelancer who is certified by the American Translators Association can earn an average of $72,000 a year, while someone without that certification will average $53,000 a year. There can also be some variation depending on just what languages you can translate. There's just more demand for Spanish translators than for Malayalam.