SEO can really be split into 2 main areas.
We have On-page SEO, everything that we do on a page to optimize for Google and Off-page SEO, everything that is done outside of a site or an article to help it rank in the SERPs.
On-page SEO is relatively simple because we can control everything that we do.
We can implement Htags, build internal linking as we link from one related article to another, add images with keyword friendly descriptions and tags and speaking of keywords we can carefully set up and optimize for our chosen keyword phrase or phrases if you are targeting multiple keyword phrases.
You are in control of how you set up for On-page SEO.
Off-page SEO is a little different because there are a few elements to this side of SEO that move out of our control the big one being gaining quality backlinks.