The main outtake here is actually very simple: write up-to-date, useful content that your target audience needs. Search algorithms are getting more and more intelligent and can, for example, give results with synonyms of the search term used. You can read more about this at Google's How Search Works.
But we can help these search engines indexing, by offering a clear HTML structure and building the content correctly by using Headers and Sub-headers. By following a number of useful guides you can make sure a website will be found better and thus gets more visitors. Factors that have influence in this are things like on-page keywords, loading speed, optimization for mobile use, internal and external references and a verbal description of images in alt-tags.