Hi denism, and thanks for asking the question. I think $6 an hour is a fair price for a beginner.
I too had to put an expected hourly rate on my oDesk profile, but so far, not once have I done any hourly-paid jobs on oDesk - can't quite get my head around how the hourly thing works. So I have applied for only fixed price jobs.
At first I worked for next to nothing, just to build up my profile and feedback from my clients - things like spend 3 hours on an article, for just $5.
I've risked doing the work first, and only getting paid after the work is done, and have never had a problem with receiving my payment. This situation needs to be looked at from both sides - people are reluctant to pay upfront, even a percentage, if they have been taken for a ride before. You can look at the person's payment history and feedback history to get a good idea if they are going to pay you or not, once the work is done. If you are concerned, don't even apply for the job - there are plenty of new jobs being posted on oDesk every day.
Good luck with the site, do some more competency tests, spend time on unique job application letters, apply for many jobs, especially when the jobs have just been posted, and not two or three days later, and when you get and do a job, do your very best work.
Over time, with good feedback on your profile, you'll be able to charge more, and get the work, due to the people hiring you seeing that you have gotten good feedback in the past.