If you have never done SEO before, read this first
Search engine optimisation is not a trick or a secret setting. It is three plain things done consistently: making sure search engines can find and read your pages, making sure each page clearly answers a question somebody actually types, and making sure enough other sites reference yours that you look like a real business rather than an empty shell.
Almost everything sold as SEO is one of those three wearing a different name. Technical SEO is the first. Content and on-page work is the second. Link building and local citations are the third. When you read advice that does not clearly serve one of them, you can usually ignore it.