Use the skills you have. Complete your profile. Give more exams and increase your profile strength. Give exams in the sectors you are skilled in. If you have a good knowledge and skill then bid for job you can do. Start small. But do complete.
It's pretty straightforward. Just complete your profile, place low bids on the jobs you're capable of doing in the given time period.
Odesk is a freelancer site, you just need to sign up and bid for the job which you able to complete it. If the buyer are interested with your bid, they will contact you
Build a solid reputation by completing jobs on time, and to the posters description. Always finish work to the highest of standards. Don't under value your skill set (if you have one) if your good at what you do, people will pay the right money for it.
complete your profile first, based on what your good at then start bidding low at first, once you get more credibility and reputation then you can increase your prices. I also recommend using other job sites as well like elance.com and guru.com. Hope this was helpful.