The first strategy is particularly useful when you have a page that has high volume of exit counts. A highly effective example is an Adsense advertisement being placed below an online tool that checks the PageRank.
The above figure shows an online tool that returns the number of backlinks when user enters a URL of a web page. The Adsense codes are placed directly under the tool. This has increased my revenue since this page has a high amount of traffic exit based on my web logs.
Why This Strategy Works?
The reason why this works is because people will start to get bored when visiting your site and they are always on a look out on other interesting resources. Therefore, by studying the top exit pages of your site, you can place your Adsense codes in those pages and convert the exit traffic (since they are exiting anyway).
How To Apply This Strategy?
You should start by looking into your web logs (in Cpanel -> AwStats) and pick up the top ten exit pages. After you have these top exit pages, look into each of these pages and experience different placement of Adsense. To help you understand how your traffic exit your page, you can try out CrazyEgg. This powerful tool gives you an overview of where are your traffic clicking and this has helped me greatly in retaining and converting those exit traffic.