I agree with some of the answers that have already been posted. The first step is writing for your audience and making sure you write something people want to read and share. That's why it's called search engine OPTIMIZATION. You're optimizing for computers, not writing for them.
The next step is to optimize, which actually could end up being step one when you conduct keyword research to identify post ideas. If you come up with good post ideas based on sound SEO research and you write great posts for people, then there's a greater likelihood your posts will rank well for SEO. At this point, you just need to make sure you use the keyword phrase in the title and write it in a way that appeals to both people and computers. You can also take a little time to optimize your post and make sure you use the keyword sufficiently in your article without over-using. The Yoast SEO plugin is great for double checking and optimizing after the post is written. Premise by Copyblogger is another tool you can use.
Recap: 1) Write posts that will appeal to people and write for your audience first. 2) Make sure to use the primary keyword in the title and in the post and write the title in a way that will appeal to both readers and Google. 3) Double check with a tool like the Yoast SEO plugin or Premise (although once you get the hang of it you don't have to check as much).
