There is no ONE thing that you should focus on so your site ranks well in the search engines.
In fact, Google uses more than 200 factors to determine the ranking of web pages!
Clearly, you will not be able to focus on all of those factors.
But there are some basic, most important factors that will work well for you.
Nick Schäferhoff, in his post WordPress on-page SEO: How to do it perfectly details nine of these factors:
- Start with the URL
- Optimize your title
- Use visual media
- Link generously
- Use keywords in your content correctly
- Create longer content
- Improve page loading speed
- Use responsive design
- Enable social sharing
Search engine optimization for pages is a synergy of many different factors. Putting them all in place involves a little bit of effort but is far from being overly complicated. Of course, there are more factors which Google takes into account. However, if you take care of everything mentioned in this article, you are greatly increasing your chances of ranking your page well in the search results.