As the one that is working and making me money, I am really starting to focus on oDesk. It's a job, yes, and my goal is Financial Freedom - and that will come from steady passive income, not pay-per-hour. But right now, I need money (don't we all!), so I take what pays...
Besides, I might have some ideas on how to make oDesk more passive. I'll post on that later though! For now, more on how things work at oDesk.
To make money there, you have to be the cheapest, the best, or otherwise unique at what you do. Considering the competition, I wouldn't try to be the cheapest - many work for under $2 an hour here. The best can also be a pretty high level... That really leaves being yourself and being unique, which means some branding. More on that in a bit.
To set yourself up, first you create an account. They walk you through that, and through the stages of building your profile - think of it as your oDesk resume. Here's mine. The focus is on what you can do for your client (called a Buyer as they're buying your services). So first I took tests to show that I'm not just saying I can write well. You need to take the introductory oDesk test, and then you're on your own. I'd recommend you do a couple obvious ones - creative writing, tech writing, etc. if you want to write. Then apply for a couple jobs and look at the other people applying - click on their names, read their profiles, and start adjusting yours. What other tests did they take? How did they write their intro? Have they worked a bit? Take their profile more seriously, like this one - notice the portfolio as well as tests.
One other thing - as you're building, don't worry about the pay. You'll get up to it. I started at under $2 an hour for my first job - now I'm at $14. The profile in the last paragraph, she started at $10 and now often makes over $30! Start. Write something. Get some positive feedback, and build. There is enough work out there to make a good career here.
Now you just have to stay motivated and working at home!