The only advise I can give that worked for me was make sure the placement is right. oh...and of course plenty of traffic!
Try this article.....http://www.novablog.info/2005/03/10/best-adsense-placement-to-maximize-clickthrough/
Improve your site with best content, traffic will overflow and earning will automatically increase.....
It's all about placements and blending. And yeah, that also depends on the type of ad units you choose to use. That's a very common question around here. Browse around and you will find more answers.
based from my experience, I got more clicks when I place link units below my header because they look like navigational menu. Adding also ad units along with your content is also effective to get more clicks.
It's about first building your content, then building links to your site so you get lots of traffic. Only then is it really worthwhile playing with ad placement and colour schemes, etc...
I suggest you try to increase the CTR. Try different ad units like, 336*280 or 250*250 etc, and put them in different ad placements. Try different combinations of ad units and ad placements to see which one gives you the best CTR.
Traffic = Clicks The more traffic flow you have the more chances of people to clicking the ads.. Tweak a little bit.. but focus more on traffic flow..