I have built a new site(finished last week, but no SEO, no clients). I know apply for ads need a long time. So I send my request to google adsense, and then do the SEO, send my site to web search. but yesterday I received an e-mail:

Thank you for your interest in Google AdSense. Unfortunately, after a consideration of his request, showed that the It is not possible to accept your application to attend AdSense.

what is the preparation of before apply for ads? Am I ignore something must do before apply for ads?

And how to apply Google doubleclicks? Or other ads service? I am newer for apply for ads. can anyone recommend me some good ads service? Thanks.