Create original, relevant content repeatedly.
Matt Legend Gemmell gives us SEO for Non-dicks:
The key thing to understand is that the rules of SEO aren’t magic or arbitrary. They’re based on the goals of a search engine, which is to find relevant results. Relevance implies genuineness, and genuineness implies trust. So, shockingly, you should try to make your site’s content trustworthy, genuine and relevant. All of the rules have come about due to their utility in detecting those three positive metrics. Good SEO is a by-product of not being a dick on the internet.