Google adsense is a best way to earn online.I earn more with it.I have many site including jobsearch sites.In my high ctr reasons there is one very important factor that is: 1-Block your adsense ads from block or ffilter adsense tabs in adsense acount.For exapmle if you have site on physics and you are getting ads of chemistry then user wil never click your ads. 2-If you have site of tecnoogy and you are getting ads of physics then user will never click as both fields are differnt. so to earn more made your ads relevent for that block all adsense ads from adsense account.Block that urls which are not relevent to your site. Relevant ads can increase your ctr....Try it and reply me if not.Go and block all irrelevent urls to your site.
My block filter is at 0 and I intend on keeping it that way. This filter is made to block competitive ads from showing on your site. Other uses at simply time wasters. Not for me, but you're all welcome to do it, be careful there's a limit to the number you can block and you're wasting your time anyway, but do it, whatever.
Instead of blocking ads, try turning on/off "Interest Based" ads on your Adsense backend. Leave on/off for minimum of 1 week to test. The results can be surprising sometimes
That works if you only have one type of site(s). If you have a variety of sites (Physics, Chemistry and Mathematics too) then you better leave those filters alone.
It doesn't matter whether you filter ads or not. Google ads will automatically be relevant to your site type.
Or, depending on the kind of site you have, they will automatically be totally irrelevant. Been talking with an advertising company about removing adsense completely and replacing it with their ad, at twice what I get from google. Someone else is paying that much on another site of mine for a page that gets about 100 visits a day, I'm sure *someone* will pay that for 10,000.