If you have decided on a blog or website and have your site up, even if it is just one page you need to get your site indexed. Indexing refers to getting the search engines to notice your site and list it.
You also need to start establishing some backlinks to your site. You can use one exercise to accomplish both of these objectives. Backlinks are the main form of off -page natural SEO. The sooner your site has a backlink the better. You will also want to show a steady growth of backlinks.