Your question highlights the TIGHTROPE experienced and competent copywriters have to walk--writing for search engines WHILE making sure flesh and blood human readers' needs are met.
First, you have to tell your content writer WHO will be reading the materials. Normally, I ask for demographic information and samples of competing or related sites that target the subject audience. I study these other sites' word choice, voice, tone, and editorial slant. I also pay attention to how the text is spaced out and how it flows. What is the value proposition? How is it presented? What is the pacing? Where is the Call to Action?
Second, I ask my client if he/she just wants to mirror the competition's copywriting strategies or do we want to stand apart from the competition. Certain niches reward an iconoclastic or quirky approach. Others reward conformity. If we are going to strike out on our own path, I adopt a persona that fits the content I've been assigned. The persona must COMPLEMENT the content instead of acting as a distraction. It must flow from the BRAND the client is trying to establish.
Third, I cluster the keywords assigned to me and I find keyword themes. I look for topical relationships with the keywords and produce THEMATIC clusters. However, I review them to make sure they are narrow enough to contain each section of the site. Of course, keywords should have low to moderate competition but pull decent traffic (this is not always doable).
Fourth, I brainstorm to find a DRAMATIC or ATTENTION-GRABBING angle within the thematic clusters and create my keyword-targeted page by page outline. I send it to the client for review.
Fifth, Once I get the green light, I outline each page: Intro, Main Body, and Conclusion. Each part must work with the persona adopted to help BRAND the site the article will be published on.
Sixth, I make sure the intro does its job - gets the reader excited about the value proposition. I then make sure the main body is well-supported by reasonable appeals to the reader's needs and the value being offered is actually appeling. Finally, I make sure the conclusion summarizes the main body's value proposition while getting the reader ready for the Call to Action.
Walk with your content writer through the process above to ensure optimal results. Remember, every WORD that goes on your client's site must BRAND the site. There is NO ROOM FOR MISTAKES.