To be honest with you the sites you've mentioned are overpopulated and so many people are established on these sites right now. If you really want to be a freelancer I wouldn't use these sites. I'd go to websites that are looking for people to write content for their sites. There are so many website owners who don't have time to write new content for their website or blog they are willing to pay people to write the content for them. If you can get established with a few websites, you'll be set up as a freelancer. Here are a few blogs you can check out:
There are over 100 different blog sites online right now that are looking for freelance writers. Furthermore, there is the online magazine and even poetry sites that are always looking for writers, graphic artists, and photographers.
If your an artist or graphic designer there are plenty of ways to earn You can try to join 99 Design if you're a graphic designer. This site allows you to use your talents and enter into contests for the best design. Winner takes all.
Otherwise, you'll be starting at the bottom and fighting your way to the top. As a freelancer think smart and don't just go to the sites everyone else goes to for work. There are so many opportunities online today to find work. You can even visit one of the hundreds of jobs board online right now and find out which website is looking for a freelance writer, designer, or graphic artist. Good luck.