I’ve experimented with two Adsense placement strategies during the past month:
1. Putting graphics on top of Adsense units. There has been a report that employing this technique can quadruple Adsense CTR by 4x. That was not the case for me. In fact, my CTR took a small dive.
2. Adding a second ad unit on pages. I found the total earnings for pages with 2 ad units actually declined. So again, this strategy did not work for me.