Personally, I'm trying to learn more about it. Robert Bly is a guy who does mostly copywriting advertising. But, he has published a bunch of books about various ways of how lucrative writing can be. Just find a niche you like.
Here is his website:
https://www.bly.com
And the one book I'm referring to:
https://www.amazon.ca/Money-Making-Writing-Jobs-Robert-Bly/dp/140221507X
Businesses will always need content and really do value a person who has a strong command of English, writing and editing.
Once you find out what you want to do just contact them on Facebook and make a pitch.
There are also websites like fiver and upwork where people can reach out to you for projects.