Increasing your AdSense earnings is often about using tactics rather than increasing traffic. Yes, traffic matters a lot; but building traffic is slow and implementing potentially lucrative tactics can happen overnight.
Using the "This Can't Be Related" Image Technique
Images draw the eyes. When people look at a page, the first place their eyes go are the pictures. Then their eyes go to the things near the pictures.
It only makes sense then to put your AdSense ads near pictures. Unfortunately, AdSense is adamant that you can't put ads next to anything that looks related to what advertisers might be selling.
That's okay. Just put images that can't possibly be related next to your ads.
For example, a giant photo of you smiling while looking at the camera. Make it stylish and classy, then put the ads somewhere near the picture.
The Below Quotes Technique
Quotes also draw the eyes. In fact, people will usually read enlarged quotes before reading most areas of the article.
Put quotes throughout your article in enlarged text. To see good examples of how this works, just look through a few magazines or newspapers to see how professional editors do this.
Then put a small AdSense block right under the quote. That quote will get read, people will see your ad and the CTR might shoot through the roof.
The High Contrast Technique
For example, let's say your site layout is primarily blue. Instead of making your links blue as well to blend in, why not make them bright red to really draw attention to them?
This will really get people to look at your ads. They still might not click, but at least you're getting the views now.
Any one of these three techniques can take your CTR and give it a powerful boost. The exact results vary from site to site and niche to niche.
Remember to carefully read the Terms of Service for AdSense to make sure you're not inadvertently violating any clauses. Whenever you experiment with controversial techniques, you really need to be well versed in what's allowed and what's not. Reread the Terms of Service (even if you've already read them a while back) before trying these techniques.