@mirona Iโve been working as a full time freelancer thru Elance for over a year now. I also have accounts on ODesk and Freelancer.com but never got a job on both. Also it seems to me (you can google that also) that Elance payments are higher then the other two. Finally Elance and ODesk merged a couple of months ago. And again, from my perspective Elance is leading the process.
That said, based on my experience and on your feedback that you are not very confident, the best move I could suggest is for you to join another developer that uses the same stack that you do, but has a better background or at least is confident enough. The reason is that you can search for jobs and share the project with someone you can discuss and even help you. Also if you apply for multiple jobs and you are lucky enough to for example have feedback for more then one and you canโt handle, you can handle it to the other developer.
On the Elance Trends page you can see the average price people charge. https://www.elance.com/trends/skills_central
Start small, try to use the average price to start. I never accepted fixed price jobs. It is risky. You might end up working three weeks for a job that was supposed to be one week only. I only work with hourly jobs. If you can get a two week job and finish, on the following week you can try submitting with a higher bid. Also on Elance, any job you want to bid, you can see the lowest, the average and the highest bids. Which helps you know how others are bidding. If the client defines a range of price, never bid lower then the minimum or the Elance algorithm will punish you.
Finally, as someone said before, a nice approach is to try to reduce your own cost the most. So that you know how much exactly you need so you can bid on what you need and not on what on whatever price clients are offering (assuming that you could bid on a project that you would receive less then what you actually need to pay your bills). On Elance Iโve seens job posts offering from 5 dollars an hour to 75 dollars an hour. Not all clients want just cheap developers.