Before anyone can address that question you have to tell us which ppc company you use to show your ads. In my experience with 3 companies:adsense, bidvertiser, and adbrite; adsense paid the highest on average. If were talking about adsense here you can't choose which ads display at all. Google chooses for you based upon your content. With the other 2 companies you can customize the ads by going into your account and customizing it. If you just poke around in those settings for a half hour and read everything they'll tell you how to do it. As for traffic, search the forums for a few hours and you'll find some good posts.