Adsense Best Practice: 12 tips to optimize for more money

Many people are using Adsense on their websites, and many talk about how many they made, why I can't even make a dollar in one day? Google has an official answer for this question.

Here's the 12 tips from Google:

1. Increase ad coverage: Placing additional ad units on your site can have a big impact on your earnings. You can put up to three standard AdSense for content ad units (note only one 300x600), three link units and two AdSense for search boxes on each page of your site. Sometimes publishers find it difficult to decide whether an additional ad unit makes sense for their site. Watch this short video to help you make sure you're following best practices, as outlined on Google’s Webmaster Guidelines, when placing new ad units on your site. As always, it’s important to consider the amount of ads in relation to the quality content on your site.
2. Use recommended ad sizes: As a rule of thumb, wider ad sizes tend to outperform their taller counterparts, due to their reader-friendly format. If positioned well, wide ad sizes can increase your earnings significantly. The sizes we've found to be the most effective are the 728X90 Leaderboard, the 336x280 Large Rectangle, the 300x250 Medium Rectangle, and the 160x600 Wide Skyscraper. Keep in mind that while these ad sizes typically perform well, you should use the size that best complements your pages.
3. Show both text and image ads: Image ads compete in the same auction for your ad space that text ads do. So, choosing to display both text and image ads increases the competition for ads to appear on your site, and may help you earn more. Check this case study to see how displaying both text and image ads helped one publisher. You can also find instructions how to enable image ads in our Help Center.
4. Experiment with ad color combinations: Choosing the right ad styles can mean the difference between ads your users will notice -- and click -- and ads they'll skip right over. There are three techniques you can use to design ad styles that will be successful for your site: blend, compliment and contrast.  Experiment with ad color combinations to find the best fit for your site. See this Help Center article for additional information.
5. Ensure optimal ad placement: The placement of your ads plays a big role in revenue earning potential and user experience. While we often recommend placing an ad above the fold, it’s also important that users can easily find the content they are looking for. Check out this resource for more tips on ad placement, and see our heat map for even more information.
6. Add a search box (or two): As mentioned in #1, you can put up two AdSense for search boxes (along with three standard AdSense for content ad units and three link units) on each page of your site.  AdSense for search is a free product that lets you place a Custom Search Engine on your site to provide users with web search. You'll also earn revenue from relevant ads on the search results page.
7. Ensure your site has a positive user experience: User experience (UX) can make or break your site’s success. With many other sites offering similar services, it’s important to differentiate your site in the eyes of your users by providing a better experience. Because a user’s attention is limited, you'll only have a few seconds to provide a good experience and quickly guide the user to what they’re looking for. Read these three blog posts to learn our top five UX tips.\
8. Make your first ad unit count: AdSense loads the highest paying ad on a page first, so to improve your revenue make sure that your best performing ad unit is the first in your HTML code. Make the changes by following these steps.
9. Fix crawler errors: Ensure that our AdSense crawler can accurately crawl your site so that your ads are as relevant and useful as possible. Visit the Account settings section of your account to see if you have crawler errors and read this blog post for details on the steps to take.
10. Go mobile: It’s clear that mobile is growing rapidly. Ensure you have a mobile strategy for your site, and use our tips and tools to help you along the way.
11. Create a Google+ page to connect with your users: Google+ offers a number of tools to help you reach audiences in new ways. On your +page, you can share your articles, photos, YouTube videos, and even host live broadcasts. Your +page will also include a +1 button that users can click to recommend you. Think about your Google+ page as a way to complement your site, allowing you to grow and measure user engagement before directing users back to your pages for more of your great content. Get started today by reading our Social Fridays blog post series.
12. Use DoubleClick For Publishers (DFP) Small Business: As your online advertising business continues to grow, you may have started working with other ad networks or doing deals directly with advertisers. DFP Small Business is a free, Google-hosted solution to help streamline how ads are served on your site when you’re working with AdSense alongside other ad partners. With DFP Small Business, you have a vast array of features that give you more control over when, where, and how your ads serve.

The above tips can be found on Google blog at here and here.