The good keywords to use are the ones that match your content and your site visitors. If your visitors are looking for paintball gear, they won't click on ads for home loans and you won't make any money at all.
Frankly speaking, "high paying keyword" email and blog post are just spam..Who will write about mesothelium and legel garbage if he dont know a FCUK about it so its better to write something that you know and love to write. Visitors will come if they like your content and you make money when the click. Content+ Patience+ visitors+ clicks =Money see money comes 5th..its not easy build it the way i told you.start with cotent and end with money
You can signup for keywordcountry.com for free trial with a email id and get the high paying keywords that is related to your website. I tried from them using the trial version and wrote some content around the keywords that is related to my website. Not bad the clicks for the advertisement is bit high compared to other pages.