Give the Ads Space

Leave a lot of free space around the ads. Even though you
want the ads to blend in with your page, you also want them
to be noticeable. Giving them plenty of free space allows
the visitor’s attention to be drawn to them. You just have to
direct their attention. Once a visitor reads that ads, since
the ads are targeted, there’s a good chance they’ll click
through.

Use Eyetracking

In general, people scan a web page the same way every
time, no matter what site they visit. Tracking these habits
can help Webmasters place important content, or even
AdSense ads, right where visitors will most likely see it. An
Eyetracking map and more information are available at
http://www.poynterextra.org/eyetrack2004/main.htm

Experiment with Colors

Experiment with the colors you use on your page and where
the colors are placed. It could be that some of your colors
divert your attention away from your AdSense ads or,
hopefully, to the ads. Use AdSense Tracker and your site
states to see which colors are helping to increase your CTR.

Don’t Label Them as Ads

Don’t label them as ads or sites sponsors. Although these
are the only two terms allowed by Google, there’s no need
to point out that these are ads. It will just prevent them
from blending in with the content of your site.
The AdSense ads are labeled as
ads; therefore, set apart from the rest of the page’s content.
Someone comes to this site looking for resources or
products. Chances are, they’re not going to click on text
that’s labeled as an advertisement. If the Webmaster feels
it’s just an ad and not helpful information, why should the
visitor feel any different?