The first thing that you should do is optimize your website for search engines.That will increase your earnings by a considerable amount. Place your adds where visitors get more impression.( you may have google's heat map of your site.)
Your AdSense profit are straightforwardly identified with your traffic. The amount you make relies on upon your corner, active visitor clicking percentage and what number of advertisements in your specialty pay.
Without seeing your website, there is so much we can say. Most of the time when your earning is low is because of your click GEO and bad placements so you might want to start working from there.