You can create different pages with different keywords to target. But the real thing is the amount of traffic that you can bring on these pages.
All of them. Any site can have pages that don't necessarily relate directly to the general topic of the site, and use a variety of keywords, one or more related keywords per page. If you already have a site with good traffic and decent search engine ranking, this is a good way to get instant traffic and start making money from new keyword pages. For example, if you have a site about Apple's iPhone, you could create a new page about "finding auto insurance prices using your iPhone." Auto insurance is a high-paying keyword for Adsense. Just link to the new page from one or more of your other pages so that Google can find it and index it,
I focus on 2-3 high pay keywords...I think it's better to have a few keywords rather than many. But who knows...
Making sites on high payed keyphrases = MFA Anyway i concentrate on 4-6 keyphrases to get rankings for each site