simply doing keyword research and your ads placement strategies,try some experiment with your ads position.But all this matter when you have good traffic http://www.techplazza.com/blog/
upload quality content, build internal links of relevant pages and bring more pages in google's main index. Traffic will explode.
Simply you need more traffic. Unique content + high quality backlinks = Traffic More traffic = More revenue
Along with doing what everyone else mentioned, play around with the ads themselves. Try out different ad placements, the ad categories, image or text links, etc and see what works better for you.
Work on creating consistent, fresh content, start building quality links, and your traffic will increase. Good luck.
Target your visitors to US, UK, Canada, Australia and other developed countries, choose the high paying keywords, select the larger/st ad size, right ad placements and increase the traffics. Details can be found at http://computechtips.com/tips-increase-adsense-revenue
More Traffic means more income. You can generate more traffic by creating original and compelling content that focuses on the most profitable keywords in your niche. As Adsense is a numbers game.