Organic SEO is the process of improving the visibility of your site’s search engine rankings via natural or unpaid for means. Organic SEO typically involves improving the content, infrastructure, or other technical elements of your site.
This means that when writing copy for your website you should give strong consideration to how your content might influence search engines finding your site. This is especially important when writing copy for your site's homepage or front door.
Search engines use the content of your homepage to determine what your website is about. Search engines then use this information and match it to 'search phrases'. So in writing your homepage you need to consider what search phrases might be used by someone trying to find a website similar to yours. In addition to copy rich in keywords, you need to give consideration to URLs, headings and sub headings, blog post titles and internal links.