1. Google’s Heat Map really does work and deserves the full attention of those who’ve ignored it. It’s really helped me improve my CTR. https://www.google.com/support/adsense/bin/static.py?page=tips.html&gsessionid=HyRs2QlabOI
2. 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 [...]

AdSense Tip #1: Find your keywords
Before serving ads on a web page, check its keyword density. A free and advanced tool for finding the most prominent keywords in a page can be found here: SEO Density Analyzer. Copy the most important keywords to a text file ([web page name]-adsense-keywords.txt).
AdSense Tip #2: Improve your keywords
Get keyword [...]