Color plays quite a big role in affecting your AdSense performance and optimizing the color of your AdSense ad units could be the easiest thing to do to increase your revenue. While it might not seem like a big change, it could actually give a big effect in your AdSense clickthrough rate.
There are few strategies in choosing the color for your AdSense ad unit. Each strategy is best for different situation, so you'll need to choose one that suit yours.
This is the most used and probably the most successful strategy in choosing the color for AdSense ad unit. The AdSense unit use the same color scheme as your site, and it should complement your site's design.
If your site has white background with grey text and blue link, the way to do it is normally to set the border and background color of your ad unit to white, text to grey, and link to blue.
Blending your AdSense unit would make it look part of your site's content, and therefore help with the ad blindness issue.
The complement strategy is to use the colors already used in your site, but the border and background color of your ad is not the same as the background of where your ad is placed.
This strategy is to use colors that stand out to maximize the visibility of your ad units. This strategy is best if your site has dark background.
When applying any of the above strategies, consider the following tips as well.
In the early days of the web, links are almost all identical; they're are blue in color. Time passed, but many people has it etched to their head that blue are the color for links.
With this in mind, using blue for the link color generally work well because your visitors know that the ad unit is a link and will click on it if it's relevant to your site and they're interested on it.
Regular visitor will generate ad-blindness to your ads over time, as they're used to see your ad to be at the same place, with the same color. It is then a good idea to use somewhat random color, or actually to rotate the colors used for your ads.
Contrary to what most think, using offensive colors doesn't always result in higher click-through rates. It's true that it might catch visitor's attention, but visitors are not fond to clicking on such ads.