What I've done is take months to build a lot of proxy sites. Lots of submission and SEO. I have a couple sites, actually my second site I ever launched, that is my biggest earner. Real solid 1-2k hits a day without and ongoing promotion. I also have some other sites that get some good traffic. Personally, I find the best way to get good traffic is SEO.
15k is throughout my whole network. I have 3 sites that get anywhere from 1k to 3k hits. And the rest are 100-800 a day or so. (75 sites).
I also have all my iran traffic redirected to one... I don't count that in any numbers, but that stupid site brings in a good solid 6-7k hits a day..lol...need to find a way to monetize that. But anyways..hopefully that helps.. I guess just age of the site has shown me the best results. Just launch em, keep promoting, and over time it will build a solid user base. My 2c