Here are some ideas to get you started (Search for these in Google and you will find more info on them) 1] Provide content that people want to read, and find useful 2] Generate more traffic 3] Optimize ad placement 4] Target high paying niches and keywords 5] Choose niches and areas with less competition 6] Read blogs of people who have made lots of money with Adsense And so on
built yourself a network and invite others to visit you in exchange of a banner or something. social network and directories submission