If you are still wondering how to cash in on Google Adsense from your site, here’s a quick checklist of items you should considering fulfilling before you can see that first payout.

Find the Best Keywords. Make use of Keyword Research tools like WordTracker or Keyword Elite to help you find the highest paying keywords that will drive targeted traffic to your site. More traffic usually results in an increase in the CTR.
Color Code Your Ad Background. Try to color code your ad’s background and borders with your site’s color theme so that it blends in seamlessly.
Color Code Your Ad Links. Use Blue for your links. Statistics have shown that blue has a higher click through rate than any other colors for Google Adsense Ads.
Mix Up Your Ads. Don’t just rely on using the images format alone as the main setting for your ad codes. It is advisable to use a mixture of both texts and images for higher CTR.
Position Your Ads. Google actually provides layout guides to show you the highest converting areas of a website. If possible, always place your ads above the fold or in between paragraphs of texts for greatest visibility.
Size Of Your Ads. Some of the more popular ad unit sizes are "336×280" ; "300×250" & "600×160". You can even try putting 2 units of "300×250" ads side by side if you have the space.
Test & Track.
The secret to finding what works for your site is to test and track all the changes you make with your ads. Make changes to only one component of your ad each time to allow for accurate testing and tracking to determine if the CTR increases or decreases.
External Stimulus For Clicking. Never encourage your visitors to click on your ads either by a call to action instruction like "Click Here" or using graphical representations like "Arrows". It is a sure way to get your account banned.
Observe & Learn.
Do a search for the top Adsense sites and see how the experts are doing, learn what they are using and where they are placing their ads for maximum exposure and CTR.

Make sure all the boxes are ticked before you start your Adsense campaign.

Have fun and good luck.