Page optimisation: is there a Golden Rule for search?

Yes but there is no single rule to follow for optimising search position.

• Include links
  There should be at least 3 links to other pages that are relevant to the topic search. See Short headlines increase engagement, SEO
• There is at least one relevant high-quality image (suitable for Social Media scrape)
  add the focus keyword in its alt description. See First impressions are fast
• Have a compelling meta description
  This will show in search results so has to make sense.
• Check for ease of reading:
  Main points first then elaborate in body of page. Make the reader's search for your article worthwhile and have them wanting to know more with short, sharp and clear points. 
• On a web page 50 words presents in the same way as 100 words on an A4 paper page:
  This means you do not have to create as much copy. What you do create must be succinct and straight to the point.