The thing that’s important to remember about keyword clusters is that they cannot and should not be used like regular keywords. If you set out to write an article that contains as many of the related keywords as possible, your endeavor will likely fail. Niche vocabulary must arise naturally from the topic that you’re writing about and your expertise about that topic. In other words, you need to start with the topic first rather than amassing keywords and trying to write text to fit around them.
With that said, by far the simplest way to create a high-authority webpage is to have an authority write it. If you are already an expert in a given topic, you will naturally use the kind of related vocabulary that Google can identify and use to rank your page. If you’re not an expert, you could find one to write your article for you. This is the model behind many successful websites, such as WebMD or About.com: Experts are hired to provide content on their particular niches, with all of that content being pulled together into a single site by the webmaster.
Depending on your situation, this may not be possible. You may not have the connections or budget to hire a team of experts to create the content for your website. Fortunately, it is possible to write like an expert without actually being one. This will require some research and effort on your part, but it’s a worthwhile endeavor if you wish to create high-quality content that will earn a high page rank and invite ample traffic from visitors.