Last week, I made a relatively minor change to the AdSense units on this site and consequently have seen 3.5-6x better CPMs... a remarkable difference.
On blog post permalinks, I used to have a 468 x 60 text unit between the post title and the article. I switched that unit to a large rectangle (336 x 280) that sits between the end of the post and the comments. That change alone resulted in 3.5-6x improved CPMs - sitewide! And that's without making two changes that are probably more significant / effective:
1) Adding that same unit to the blog's homepage and placing it between posts 2) Nesting the unit within the article on post permalinks (like below)
Other considerations: - Testing the color and formatting of the unit - Test rotation of text, image and video ads (all exist for that size) - Adding Google Links Ads (you can have three text / image ad units per page and three link units)
Have any AdSense best practices?