When I purchase advertising, I only do it on sites that have an auidience I believe would like my site. That is why I don't do so much with Adsense and the likes, even though Adsense has contexual advertising. Usually I will prowl the net until I come across a site I think would be good, check it out for a while, then inquire about advertising. I find this way to be much more responsive.

So, what do I look for in a publisher? A site that has a similar auidience as mine.