Although Google doesn't release exact details as to how they determine the ads to serve on a given page, they do tell us that it's the text content of the page that matters, not the meta tags. Before serving ads on a page, then, you might want to check its keyword density. A good, free tool for doing this is found here:

http://www.ranks.nl/tools/spider.html

This lets you fine-tune the page before exposing it to the AdSense crawler.

BTW, my favorite keyword tool is Keyword Elite:

Rapidly Generate High Paying Adsense Keyword Lists Of More Than 10,000 Keywords In As Little As 2 Minutes And 57 Seconds!

When it comes to content, take the time write the best article you can. Don't write a bunch of rehashed garbage that's already been copied 100x before by lazier webmasters then you. Write something fresh and recent with new sources. Also, don't make the article short just because you don't like to write.

Write until you've exhausted the subject. This will help you avoid duplicate content penalities, increase the stickyness to your site, and put out more 3,4,5, etc. keyword combinations that you can pick up traffic on.

Wanna get FREE, UNIQUE, QUALITY content fast? You will be able to maintain HUNDREDS of Google Adsense sites, try this tool for FREE:

ContentSolution - this is my reason of success in Adsense.

We all know that web-savvy (eg. webmasters or people that use the Internet for so many years, and know all the standards, convetions and so on) users are ad-blind.

Banners like 468×80 have been on the Internet since it's creation. Even people who use the Internet vaguely or once a month, are kind of blind to these standard banners.

Instead, use vertical skyscrapers, or boxed ads. They have a much higher click rate. The Adsense team even published a list of their highest performing ad sizes:

* 336×280 large rectangle

* 300×250 inline rectangle

* 160×600 wide skyscraper