In September 2010, about seven years ago, Google released their "Search Engine Optimization Starter Guide", here is the PDF download. The document probably has not been updated since then and the copyright on the document still says 2010.
When Gary Illyes from Google was asked if the document is "still relevant/best practices" Gary said yes it is.
Yes
— Gary "鯨理" Illyes (@methode) August 2, 2017
Here is the copyright on the footer:
Typically, most core technical SEO has not changes over the years. There are things like schema, rich snippets, markup and new things that have come out since then that may have changes. But the core principles on making search engine friendly sites is still the same as it was since the early days.
So reading this document, which I have not done in several years, is probably still relevant. At least, Gary Illyes from Google said so.
Forum discussion at Twitter.
