I used HP as my work portfolio. My more serious work are on this site. I have my own blogs for other types of articles. My daughter, who must be the same age as you, writes full time. She earns a respectable amount from those 3 sites that I mentioned, specifically iwriter. But she is an elite plus writer who is ranked among the top ten highly rated writers of the site. You can also try essays.com. It is Philippine-based but pays lower.
The WAHM website is good about posting legit work-at-home opportunities, although I don't know how many of them are open to international residents. Might be worth checking out, though. http://www.wahm.com/jobs.html
They also have a forum where you can discuss opportunities and experiences with others who work from home -- in other words, find out about scammers before you take the plunge, and learn tips to increase your chances of landing jobs at different websites or companies. http://www.wahm.com/forum/