The most important part of SEO to be mindful of is this: Think of your user first.
It’s easy to get caught up in keywords, and one might think more is better, but remember the ultimate purpose of your website is to be a tool for your clients. Craft thoughtful, well-written, entertaining, and/or educational articles with real people in mind. Be aware of search engines’ roles in presenting this content to your audience, but don’t write specifically for the robots crawling your site.
If you’re just getting started, Google’s SEO Starter Guide is an excellent beginner’s tool. It defines terms, how to view results, and how to get your site on Google.