Try not to have any other links “above the fold”

This may not always be possible. But if you can, remove all links that are “above the fold”. The only links displayed should be your AdSense Ads.
By having any other link, you are giving your visitors the option of clicking on them. This will decrease your CTR.
If you do not have any other links,your visitors will sub-consciously be forced to click on your AdSense Ads. This will shoot up your CTR.