Add additional content to your website which targets related high paying keywords:

The most important word here is related. Don’t add content pages about Viagra to your website which is themed around motorcycles just because the average CPC for Viagra is very high. Instead do one of these two things:
1. Type your primary keyword, in this example, "motorcycle" into Keyword Country, wait for the results to appear and then click on CPC. This will arrange all the related keywords by their CPC value bringing the most profitable to the top. I did this and found that -
“Motorcycle Insurance In Michigan” has an average CPC of $10.25
“Motorcycle Insurance” has an average CPC of $4.28
“Motorcycle Loan” has an average CPC of $3.34
These are very high average CPCs for which you could develop new content. These content pages would generate higher cost per click Adsense ads from your visitors.
2. Your second option is to type in keywords which are related to your principal topic. Continuing with the motorcycle theme you could type in Harley-Davidson a popular manufacturer of motorcycles. The results show that “Harley Davidson Boots” has an average CPC of $0.84. You could build a page today pre-selling Harley Davidson Boots and generate a nice Adsense stream from that page. Another extension would be the keyword “chopper”, a popular type of motorcycle enhanced by the big shows of the last few years. On Keyword Country a search for chopper brings up related keywords like West Coast Choppers, a famous chopper builder which has an average CPC of $0.95 – again a page or several pages around this topic would be a nice addition to a motorcycle based website.
Whatever your topic, virtually every website can incorporate new high paying content. So before you try and build a website in a new niche check that the website(s) that you’ve already put the groundwork into (link building and seo) can’t be better optimized for higher paying keywords and / or have additional high adsense paying content added to it. There will be at least five new pages of content that you could add to your existing website today that would create higher paying average clicks than what you are already generating.
The large majority of Adsense Publishers are still not taking advantage of these tools and are still working in the dark so to speak - unsystematically adding content, optimizing their pages and building new niche websites with no fore-knowledge of the value of a particular topic nor its potential profitability. I guarantee that if you test Keyword County for just a day you won’t want to unsubscribe - it makes our job of making money with Adsense that much easier.
They also have a free “sneak peak” tool whereby you enter your target keywords and it will give you the most high paying keywords related to that phrase. If you follow this link and click on the “try now” button in the top right you can test the three different parts of the application yourself.