This isn't by any means a comprehensive list.
I'm sure there are many ways to game the system that Google hasn't found out about... yet. There always are. AdSense is constantly changing to find new ways to detect click fraud, and eventually you will be caught.
The best way to generate income through AdSense is to create good content that is well optimized for search engines and to promote your site through legitimate channels.
That sounds like a lot of work, because it is a lot of work. However, it's a strategy that won't get you banned.