• Your AdSense earnings are directly related to your traffic. How much you make depends on your niche, click-through rate and how much ads in your niche pay. 
• Do experiment with Ads Size in your site, which one is best works for you. 
• Use ads blocker to block your compactor sites

• Don't compare earnings. You cannot estimate your earnings based on someone else's traffic because every niche is different. 
•  Three units is not always best. Even though AdSense allows you to use multiple units on one page, that doesn't mean it's always best for your user experience.
• Also, Google has been known to penalize the rankings of sites that have too many ads (especially near the top of the page). Learn to balance your ads with content. You don't want to run people away by appearing greedy with ad overload. Not to mention it looks unprofessional. 

Diversify. While AdSense can be a great way to earn additional income, you should also diversify your income streams.
Not only are earnings unpredictable but you could get your account disabled and lose everything at once.

• Find The Right Theme. Rather than trying to tweak and manipulate your site's code, it's best to find a theme that already has the placement setup for where you want to put your AdSense ads.