How to I increase my adsense earnings?

Answer 1

1. Add other revenue/monetization models (CPA is one, but not the only thing out there)
2. Get more visitors (more visitors = more clicks = more money, especially if you begin to incorporate other models)
3. Target higher paying keywords (there are some in every niche, you just have to find them)

Answer 2

Increase your traffic / visitor for your site; make best content; increase backlink; make a group in social network like facebook etc, then make a group with a lot of member;  comment in other site / blog