To make money from adsense, you have to do 2 things:
always trying to use high paying topics
always get triffic for your site
then your money comes
Here some experices:
Asking Questions At Discussion groups
There are tons of online discussion groups where leading world experts will answer your questions and give you valuable insight for free. It is amazing why most people do not think of using these online forums to learn as much as they can about the most effective ways of making money from Adsense. You can add your signitures with your sites.
These forums can easily be found through you favorite search engine.
You also can try make some questions with high paying niches, make some intresting questions to bring more trific to your web sites.