Secondly, on every job/bid ,personalize your communications with the employer. Don't send standard bids/messages that i am the best, i have done this this this etc. Make the employer understand how you are best for THIS job. make them you realize you know what they want and that you know what you are talking about. Tell them about RELATED previous projects. Giving them a feel that you are an expert in this sort of stuff helps a lot. A good personalized communication helps beat many mighty competitors with tons of reviews under their belt. I did that several times and it plays well with people's fears that a big shot freelancer would not dedicate his time to my project.

Thirdly, getting that first job may take a long time. Don't lose your hopes. that's just how the freelancing community works. when you don't have any reviews things get tough. But that is exactly when that personalized communication comes in very very handy.

Lastly, don't be afraid to demand some protection from the employer. it's your right. So make sure the employer puts the money in escrow before you begin any serious work.

One piece of advice, and just not about oDesk. Do reasonable work, don't silently miss deadlines, and always set expectation and communicate (never hide).

I've worked for some big-name Valley companies. If you just follow the advice above, you will be far ahead of the pack. (And that's even more true in the freelance world.) Good luck.

If - nay when - you screw up, admit it right away and figure out how to fix it. It really will make a huge difference in how useful you are. Goes for other parts of life too.

Step 2: Do what you said you would do, by the time you said you would do it, for the price you said you would do it for.

Step 3: Tell the client that you've done what you said you would do, by the time you said you would do it, for the amount you said you would do it for.

This alone would make you a stand-out in the world of free-lancing. For bonus points, keep the client updated regularly via a single page report, at least weekly, of your progress, of project risks, and outstanding issues.

Just something that proves you know what you're doing.

I haven't hired developers, but I've worked with several writers. Quite a lot of the ones I've worked with didn't have previous work experience but they had sample articles uploaded for me to judge their skill and style.