From what I remember from a translation job, it is free to publish your job, and you only pay when job is done.
You should ignore 99% of the applications you will get though, and you should proactively ask to the best rated workers to do your job instead (offer and demand rule :))
Good luck
So… I posted a job (again, because the first guy did not deliver) on freelancer.com
This time I included the following at the bottom of the Project Description: “Your first line should be ‘I like games’. This is so I know you have read the application. If you do not have this line, your application will be deleted”
Here is an example reply:
“Dear Sir I have job description very carefully and found that I have qualified enough for handling your project…”
Wait? What ? Isn’t it MY job to determine if the person is qualified to handle the project ? 
Freelancer.com is a great place to outsource work but you need to be careful.
If you have a good enough budget you will get A LOT of bids. From so many bids, only a few are worth looking at (the ones with the most and best reviews).
If you have limited budget you will get fewer bids and most of them will be from people looking to provide bad services for quick money. There are chances you’ll find a great person to work with for a limited budget but the probability is very low.
No matter what budget you have, you will need to be patient and analyze things in detail, talk to people, see how they respond.
A general rule to find good service providers: if they want to know the budget and they talk about payment very fast it’s usually a sign that you should NOT work with that user. The best ones first ask a lot of details about the job in order to give you a precise price.
You also have the option to create private projects when you invite only one person. You have a higher chance of getting someone good for the job but the price might be higher than what you might get from an open project. To find a good service provider, search the directory on freelancer.com and filter them by number of reviews, rating and portfolio.
Good luck!
I use oDesk exclusively now and don’t have too many issues these days. It took me a while to get to this point. The easiest way to find someone for me is to list your job and get rid of everyone with an automated response, they are easy to spot about 80-90%. Then ask if they are solo or part of a team. You would be surprised how many developers are using someone else’s account. This is not bad if they are part of a team and you can work with the others if one gets sick, but be careful if it seems scammy. The last thing is to tell them I need a splash screen for my app with these graphics and see how long and how much it is going to cost. This sample job can tell you a lot, while it can’t tell you everything it weeds out about 90%. You should be down to your final developers and now you pick you and hope for the best. If they do a great job, make sure to hire them again! Even the great ones can flake out after a few jobs, so there is a steady churn of developers.
Just my experiences, I have done alright so far with very little problems.
How do you pay people - if you don’t have paypal available in your location ?
Do Odesk or Freelancer etc. handle payments as well - i.e. they charge your credit card and credit the person you hired to finish a job etc. ?
They usually support several payment methods including paypal, moneybookers, wire, check, western union or credit cards. The money is deposited on the website and is then sent to the freelancer in an escrow account. Once the job is complete you release the escrow payment, the money hits the freelancer’s account and then the freelancer can withdraw the money from the website using different payment methods.