According to adsense coach Joel Comm, ads that bring the highest ctr, are the ones that are blended in the best. Placing ads that are easily struck as ads do no not work as well.

To blend ads to your site make the color of your ad titles the same as the color of your text title. Also make the website links the same color your ad links. Blending your ads with the colors of your site will make them less noticeable as ads and more likely to be clicked.

Another method Joel Comm uses is to use a blue ad links color. Over time people have viewed blue ad links and now recognize the color blue as a color that is meant to be clicked. In other words, when people see blue, their mindset tells them to click, or rather the link is meant to be clicked upon. The blue color link is encoded by the code #0000ff.

Good luck with this technique. Make sure to note that every website is different. There is no right color for any blog. The best results come from experimenting with different colors. Many sites may succeed with the color blue, but others may see better results with a different color. It all depends on the layout and design of the website itself.

Cheers!