While Google is a nice partner to work with, they are strict on a number of issues.
* Once you implement the code, do not click on the ads yourself. Given the amount that some advertisers are willing to pay, Google is very, very sensitive to click fraud.
* Tell anyone else using a computer from your home not to click on the AdSense ads, just to be safe.
* Do not ever, ever try to "game" the system. Google is well aware of most of the tricks people use to engage in click fraud and pursues those people vigorously
* Don't implement AdSense code where no-one will see it.
* Don't incentive AdSense ads by offering rewards to visitors for clicking on ads.
* Don't beg for clicks e.g. "help support this site, click on this ad"
* Don't place AdSense ads on an empty page.
Any of the above can result in your AdSense account being suspended.
* Customize your AdSense ads, don't just use the default settings.
* Write your content with not only the reader in mind, but with Adsense considerations as an issue.
* Don't be too concerned with AdSense ads taking away from other offers on your site. It's been my experience that if people are interested in your content, and in the AdSense ads, they'll finish reading your copy first, then come back to the ad if that's of interest to them.
* See AdSense as a partner, not a competitor. If you don't have what your visitor is wanting, while you may not get a sale, you may still generate revenue from that visitor by using AdSense.
* Positioning is important, place the ads where they are most likely to be seen.
* Google allows you to place up to three instances of AdSense code on each page - use them if you can, but vary the type of implementation