Personally I have had significantly better results with oDesk.com instead of freelancer.com. I don't know exactly what it is, but it feels like they have better values, and thus better clients.
A key point, that was a breakthrough in my career, was when I launched my new cool and modern website explaining services and portfolio. Then I started to receive random clients interested in my values.
What I am sure is that you need to build a portfolio. If you don't like freelancer.com for that, try with little personal side projects, open source projects, or doing work for friends for free/low prices.