This is a great question. A question I've been trying to find the answer to for years, literally. Still nothing. I am trying out blogging. With blogging it's a matter of having enough quality content to write about and how frequently you can blog. Also, the SEO and Ads.
I tried www.textbroker.com which has an easy format. People post topics and descriptions they need something written on and someone else chooses it and writes it. Simple, but the pay is low. $1-5 per piece depending on what text broker has rated you as. Pay depends on your rating. It's easy to make the money, but almsot not worth the money.