A few people have written in asking how I got the chance to write for Twirlit, Vivastic, PhysiqueSpeak and AdventureWorthy.
The basic answer: start a blog! Like in screenwriting, you're never going to get paid to write unless people can see samples of things you've already written. Because of my blog, I met another blogger who eventually became editor of one of those sites. She liked my writing and hired me on. As the company expanded and started more sites, I was referred to the editors of those sites too.
A lot of websites pay very little for online articles (especially ones that aren't real journalism, but link to bigger sites and provide more of a commentary), so the key is to write quickly. Don't accept any writing jobs that don't translate to a decent hourly rate. Writing your own blog won't pay anything, but at least you'll enjoy creating the content. Also be wary of any sites that will pay you per click (unless maybe it's a bonus in addition to your base pay). You don't want to spend all your time begging people to click on your articles.
You probably won't be able to make an entire living from blogging or writing online. I started out just doing a few articles a week, and even when it blossomed into daily writing, I had to pair it with tutoring and other part-time work.
You may also want to check out my blogging tips from December!