At first indexed your site in Google web master. Then you start SEO to promote your we site. SEO off page activity help to promote your site. like Web 2.0 submission, forum posting, guest posting, Blog posting, Blog commenting etc.
I suggest, at the same time your doing with these things, that you partner with other recruiting agencies, that aim the same industry.
You can create youtube videos, PPC, blogging to create a following. You can post on forums. How about creating a blog and start a following through explaining why become a contractor and also why should people get jobs done on your site.
Go to your "competitors" sites like oDesk, eLance, Freelancer, and see if they have banner ads for sale. That's THE most targeted traffic you are going to get. Cheers.
Try and maintain these steps : Create new and original content update content frequently add content even if your site only sells products format the content Just follow this then you'd be glad I shared this to you
I need some suggestion on initial promotion of website so we can at least get 400-500 sign ups from freelancers.
Got pretty decent traffic and sign up from FB groups. And the lesson I learned is, on FB group the browsing is very fast so 300-400 word article describing your website/product is useless. I just used 3-4 catchy lines and url at the bottom