The best 3 method to get high AdSense CTR

There are so many ways people suggest on how to get a high CTR, andI've learned it for some time and try to put some methods into actionto make my CTR higher ..

And these are my best 3 method
1. Ad Units Placement : below the header, on the top of left side bar and inside the articles.
2. Focus on a few keyword
3. Content 'fine tuning' - to make ads highly related to the main keywords and page content.

What about you? please share your best method to get high AdSense CTR.