Secure your adsense account using these tips :
1) Do not click your own ads or do not do your own impressions.
2) Do not encourage anyone to click your ads.
3) Avoid using or exposing adult content, violent, racial, discriminating, harsh content in your sites.
4) Avoid from AdSense Code being change.
5) Write something fresh in your site and avoid copy paste. Do it yourself like Mr Bean.
6) Follow the Google policy. This will make Google trust you more.
There are actually more ways to prevent your account from being banned by Google Adsense. So follow these tips and earn your adsense income passively today!