When the objective is to earn from Google adsene, its better to follow certain guidelines during the development of the website. The fundamental philosophy of any such contextual advertisements is to display advertisements depending upon the relevancy factor of the website.

A proper content will fetch the proper relevant advertisements from the advertisers or sponsors, which are routed through the advertising engines.

So, you can easily expect the advertisement of a search engine optimization company or individual, if your website addresses at the issues of search engines or web solutions, as the ultimate goal of any web solution is to get a proper rank in the search engine result pages by a continuous efforts for optimizing the website for search engines.

It is not only the content, the Meta tags and the other tags like H1, H2, IMG, ALT, TITLE need to be also properly tuned or optimized. Let us take and example, the image name web-crest is much more preferred than header1.

An ALT tag should be indicative enough about the purpose of the image.

If a gif image of a college building is displayed, the ALT tags like college-building or college-premises are much more meaningful than img1 or img2. 

Remember, when search engine sends its crawlers and spiders to your website host for a routine visit, it never shows the luxury of ignoring any such tags, rather it sends them to the database of the search engine for a better comprehension.

When Google adsense tries to find the keywords for publishing relevant advertisements, they also take a note of all such tags. Never forget that the bold words in your web page also carries significance while determining the relevancy factors.

Last but not the least, whenever you are talking of keywords and content, there should be a proper match. It should NOT happen that your content aims at an educational endeavor and your keywords become adult games. Such conflicts also confuse Google Adsense and then you might find irrelevant and unnecessary advertisements, which might even annoy your visitor.