I have compiled some really useful tips which I have tried them or some of the members of SPF / DP / WMW have tried and seen good results with.

We get lots of threads where people ask for such tips and mod if we can make this Thread Sticky.

1. Always use Google Heat map as it really works.
   
2. Write original content and not the ones which are found everywhere and Invest in content as that should be of highest priority.
   
3. Remove unnecessary links from the pages having Adsense as you don't want users to click on anything other than Ad if they want to navigate away.

Read all of them -
Useful Adsense Tips

Any example of unnecessary links made in your third point?

Yes. I switched off the signature links to Guests for sometime which made clicks into the Adsense Link Unit to rise for a week or so and then when I switched it back on it went back to normal which means that when users are done with reading what they are looking for they tend to visit other sites if they are not fully satisfied to the topic content and if they see related Ads they visit them.

Another tip is to limit the number of ads per page. Too many ads will let lower bids onto your page causing you to have lower $/click.

Originally Posted by altesino

Another tip is to limit the number of ads per page. Too many ads will let lower bids onto your page causing you to have lower $/click.

Yes its already there. Read the complete List.

one add with 350 or 250 block is wondering.

Good to know. Didn't even think to cut off all the links I have on the site. Thanks for the tip.

Originally Posted by tchoppy

Good to know. Didn't even think to cut off all the links I have on the site. Thanks for the tip.

Even I realized many of them after lot of experimenting.