I'm an SEO specialist for 10 years. I have own blog about SEO. My favorite article about On-page optimization.
To make your website competitive you need On-page optimization. It is a complex of works aimed to build resources in accordance with search engines requirements. On-page optimization makes your website search-friendliness. In fact, all elements form a summary for search engines about your resource and in result Google can understand what the site is about and what words characterize it. About all On-page optimization factors you can read in this article https://www.linksmanagement.com/onpage-guide-tutorial/