I have managed to boost my CTR to around ..... (can i disclose it by adsense TOS?) Well for me the trick was to: 1) Find a niche or at least make sure you dont have much competiton if you want higher CPC. 2) Its all about quality traffic. SEO/adwords is a key because people who end up on your website are looking exactly for the service/product you provide. 3) Experiment with adsense formats, colours and placement. 4) Be patient. Google needs time to spider your page properly and feed relevant ads. So what i do is test a particular ads setup for 2 weeks or so and then move on. Dont forget to note the setup you had in order to compare it to others. 5) Never give up on testing more setups. The possibilities are endless. When you find what seems like a perfect setup you can always do better still. Dont know about others but this works a treat for me. Now one of my smaller (200 daily uniques) site gets more money per week than my larget (500 daily uniques) per year.
thats pretty good advise, but dont overflow you site with ads then people will not come and look at your page.
I believe you are allowed to have a maximum of 3 Adsense ads per page. But this doesn't mean that you have to have all 3 displayed. Sometimes less is more.