Key Adsense Site Strategy Point
Build some pages on very high paying Keywords. Write articles on related keywords that are not as competitive and not as high paying. Then submit the cheaper keyword articles to article directories with links to your Expensive keyword pages.
Get traffic from less competitve keywords lower paying keywords to go to very high paying adwords pages. The Google ads on the page will be relevant to the page, not the page from which the viewer was sent.
This sounds really simple but it is more thoughtful than first blush.
High paying keywords are usually very hard to get ranked for. Use long tail words that are easy to get ranked for and send the viewer to the higher paying related keyword page.
How do I figure out what is a high paying adsense keyword? I use the free Google Keyword tool. This tool is your friend. Spend some time playing with all the different buttons and windows on the Google Keyword Tool. Long term this will be time very well spent.