I've never worked in Elance but I have worked in outsourcing sites like oDesk and Guru. Yes this is a good idea as part-time jobs. I do this as part-time jobs for an extra allowance. Well, although it's not that big, it's still helpful. It's quite competitive since you have to compete with other freelancers and they already have a lot of experiences and do have a big rate already. So what I did was to rate myself low per hour. So when I have the lowest bid on projects, they hire me (I just do simple jobs like article writing, blog commenting and forum postings) because of the cheap price. So when they hire me, I will make it sure to do the job well so that contractors will give me a good feedback. Eventually when I already have a good rating and good feedback from contractors I've worked with, I then increase my hourly rate.