If your like me and have been working on several blogs, or domains trying to build traffic through keyword writing. Then this might be a helpful read for you. I have done a considerable amount of research, and feel that I have a pretty good grasp on what and where people click. The three highest performing ad units are the 336×280 large rectangle, the 300×250 inline rectangle and 160×600 wide skyscraper. Consider this when selecting which theme you are going to use. Be unique if you can, customize the theme so it stands apart from the rest.
The most successful link color is blue. This has to do with the roots of the Internet where all web sites used blue hyperlinks.If you use other link colors make Adsense links the same as your normal links.
As a general rule blend (no border, same background) your Adsense units if your website has light colors and contrast (border, contrasting background) the units if you are using a dark color scheme.
Ads in context should not have borders, while ad units in sidebars can use borders to attract the eye.
Test, test and test some more. Each website is different so test with different colors and formats and keep track of the results to help fine tune your Adsense earnings.