Simple , you need to have high paying keywors like money niche or maybe insurance. These are high paying niche or you could actually follow what i said at my thread http://forums.digitalpoint.com/showthread.php?t=1097768 I made more money using my method . It's so simple people tend to forget.
Place some high paying keywords (HPK) on your meta keywords... Niche articles like insurances, lawyers, credit card, loan for student, car insurance or cancer therapy can help your blog to earn more money ...
Mainly it depends on your niche but there are other factors as well such as source of traffic. Try to improve by targeting rich countries such as the U.S., Canada, Australia where advertiser will probably bid higher for the ads.
Get information on high paying keywords from here. http://forums.digitalpoint.com/showthread.php?t=1097949&highlight=high+paying+keywords.
I you want to know How to improve your CPC you would publish articles on your site, include high CPC keywords relevant to your niche in it.
It could be that you suffer from adsense smartpricing. That drastically lowers the amount of money you get per click. Placing high-paying keywords in the meta-tags is not a good idea. Don't place anything irrelevant to your niche in there. Make sure your website is related to one niche only, remove all advertisements from general pages. Doing so will get more relevant advertisements and consequently higher CPC. Good luck - smart pricing sucks.