How Google Adsense Click Fraud Can Ban Your Account.

If you trawl through the AdSense message boards you can't help but come across tales of woe from AdSense publishers that have had their account banned by Google.

Below is a list of ways people have been banned from AdSense and information on how to avoid it happening to you.
Don't click on your own ads
The obvious one but still people do it. Google has the IP address of the computer/s that you've used to create and check your AdSense account. If it sees that this IP address clicks one of your ads you're in trouble.
Don't do it. It's theft. Not from Google but from the AdWords advertisers.
If you want to go to a site advertised by one of your ads don't click on it look at the URL of the advertising site at the bottom of the ad and type it into your browser.
If you click on one accidentally (which does happen) you're probably be ok but it's worth dropping a quick email to Google with an explanation and apology
Don't log in to AdSense from a shared computer.
As I said above Google keeps a record of every machine IP address used to look at your account. If you check your stats on a machine then someone else clicks on your ads from the same machine Google sees this as click fraud. Worth bearing in mind when thinking of checking your stats from somewhere like an Internet Cafe.
Don't log in to your AdSense account from work.
Apart from getting in trouble with the company that employs you there's also a further real risk. Most companies use a proxy server to access the Internet. A proxy server with ONE IP ADDRESS. Therefore you checking your ads from work means this proxy IP address being recorded by Google as one that you use. Problem is if there are 1000 people in your company it is the same IP address for them too. Google can't differentiate between you and the other 999 employees in your company. If one of these 999 clicks on one of your ads its ban time.
Don't get into an I'll click your ads if you click mine agreement with another Webmaster.
As above Google will have your IP address and that of every AdSense publisher. If they see these IP addresses consistently clicking on each other ads it's goodbye for both of you.
Don't tell friends and family.
Telling friends and family about your money making websites can lead to problems. Even if you tell them not to click on your ads there's always the chance that Auntie Maud will think it's a good idea to make some extra money for her favorite nephew. 100 clicks later from the same visitor and your account is screaming Click Fraud
Receiving clicks from illegal traffic
Check the AdSense TOS for sources of traffic that aren't allowed by Google. These include methods like Traffic exchange, PTC advertising, Auto surf etc.
Do monitor your visitor and AdSense figures
Check your account at least once a day. If you see a massive spike coupled with a massive increase in Page CTR investigate using your visitor stats website. If you see it's all come from the same IP address you could have been the victim of a malicious attack inform Google via email and offer them access to your logs.