No one knows 100% what Google wants from your site in order to rank it highly, their algorithm changes frequently & you have to change and adapt too if you want to be successful. There are many different aspects to SEO success and no magic formula, but you don’t have to reinvent the wheel when creating your SEO strategy, there is help out there.
One of the best resources for up to date news & tips on best practices is Search Engine Land. Recently they published the Periodic Table of SEO Success Factors, a fantastic guide to which elements, both on & off page are most significant & which Black-Hat practices could get you penalised.
Infographic By: Search Engine Land