if you are doing freelance works along with your regular work then don't leave your regular work until you are financially strong because in freelance you may also have too see that some times you may not have any work to do.....
Also, don't stick with only one freelance sites, if you are not getting clients then you can use other ways as well like forums, creating your service sites then optimize them with the main keyword so that you can also get some clients from search engines.