adsense ad placement

The Basics of Using AdSense - Location
When you place AdSense on your site, you should look at the task as though you are providing a resource to members, not simply trying to generate income from their clicks. For this reason, you’ll want to target the areas that visitors tend to look at first - sidebars and headers. Visitors that don’t see an ad won’t click on them, either.

Here is a rather brief look at general placement options for most blogs:

Sidebar - The sidebar is one of the most critical placement areas for ads - the second most looked at location right after the content. Ads should be placed in a logical manner, blending in with other similar links or used in a way to attract attention to them, while not overwhelming your visitors with “flashy” graphics.
Between Blog Posts - These ads will display in-between each post (up to three times per page), with nearly every size available, from 120×90 pixel buttons to 300×250 rectangles. There is a good chance that visitors will notice these, thinking they are still a part of your content.
Header - A blog’s header should remain as clean as possible, distinguishing your site from others from the time a new visitors first appears on your site, but it can also be a prime location for placing ads. Generally, the best sizes are 468×15 (up to five links) or larger, as the content/links displayed will be generated from the keywords that have been placed in your header/first posts.
Menu - 728*15 ads in place of the menu in header or just beneath the header will work the most if used in that spot. This will really increase Adsense earnings as the spot and the ad resembles as if the menu of the website. Many readers of your blog may not like placing ad in that position but still if we need to make earnings from Adsense we need to find such most important spots for Adsense. (Thanks BLOGGERUSER)
Inside Blog Posts - If we display Adsense ads inside post, it is found that it has relatively higher CTR. People mostly think this ads as a part of the content and click it often. And these ads have almost related words to the topic or key words you have in your specific blog post. (Thanks CELEBSIMAGE)
Feeds - An area often overlooked for ad placement is in feeds. After all, there are many sites that have thousands of subscribers - people who normally don’t visit the actual website each day