Google AdSense team provided following tips to help you to optimize your AdSense implementation. "If you're interested in trying out these suggestions, sign up before Dec'15th. An AdSense optimization specialist will contact you by email or phone to implement the tips you want to try."
First, note, that you're allowed to put three standard AdSense for content ad units, three link units, and two AdSense for search boxes on each page of your site.
Choose right ad units for your pages: wider ad units perform better because they: Are easier for users to read and interact with; Allow more ads to be displayed within a unit; Are preferred by advertisers designing image or video ads
Also, remember to opt in to display text and "image ads," as this increases the pool of advertisers competing to appear on your site.
Improve your AdSense implementation by increasing ad coverage on your site.
- Put ads on pages that don't currently have any, as this increases the chances of monetizing your site's traffic.
- Placing ads within the page content or article text, or near the navigational areas of your site, can strongly increase ad performance
- Use link units to monetize the smaller areas on your site.
- most effective -- put at least one ad unit above the fold -- the section of the page users see without scrolling down.