In my opinion, the safest site for outsourcing work is freelancer.com and Odesk.com. Its legal and payment is guaranteed.
freelancer.com is one of the best previously but they are getting worse and worst now odesk.com and guru.com are better, try them out
Whichever service you choose or think is the best, reading the terms of service of the ones that interest you is extremely important, as they can and will determine what can and can’t be accomplished.
Yeah, odesk is good but it is not easy to get a job right away.. There are many competitors so you need to make your profile very attractive to employers.