I heard that you can increase your CPC by blocking certain Ad Networks (the ones that only have like $0.01 CPC) Which ones are these or how do I found out which one they are?
In adsense go to Performance Reports -> Ad Networks, order by clicks descending then analyse the data for CTR/CPC/RPM - it'll give you a good indicator of which networks you use and which have the best performance.
I would advice to block NOTHING and let adsense do its job. Use your time on adding content to your sites.