Wasting time looking for a 'high paying keyword ' is a typical newbie mistake, which I have also made.
I finally found a high paying keyword, created content around it only to find that advertisers for that high paying keyword had 'content network turned off' OR they were excluding my site from their adWords interface. All I got was MFA with 2-3 cents clicks. What a waste of time!
I now focus on what I can do best, the clicks and traffic develops slowly. I am happy with 10 cents cliks and sometimes manage a few 50 cents and 80 cents clicks also. With a decent volume, it turns out to be a good aggregate figure.
Try to focus on quality and quantity of your website and forget about chasing high paying clicks.
Of course some subjects like financial services, lawyers, real estate, stocks etc pay well , but not everyone can create an 'authority' site on these topics.
You may keep experimenting and will hopefully settle down fast.... There are so many variables in the AdSense and AdWords program that it is almost impossible to GET RICH QUICK....unless you are very very lucky and very very smart..