Google's final optimization tip: Monitor the performance of your account, evaluate the results of your ad campaigns, and plan your next steps based on the assessment results.
Of course, you start tracking the performance of your ad units using Channels in your Adsense account. You use channels to compare performance of ads of varying types (should I use banner or leaderboard ad?), in various locations (should I place the ad at the top or bottom of the site?), and in different site pages (should I change the format of ads to be used in the Contact Us and About Us page?).
But you should not be restricted to the features within your Adsense account. Utilize Google Analytics and be able to see who's coming to your site, where they are coming from, how long they are staying, and in which pages they are visiting. Google Analytics helps you implement changes to your site by providing detailed statistics and analysis of visitors to your site.