What tips and tricks would you recommend to optimize for semantic SEO?

Selected answers from the Dumb SEO Questions Facebook & G+ community.

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  Rommel Badua: Hi there! I'm currently updating our corporate website (not a blog), using HTML5 & CSS3, are there any new Meta tags that I should include? What tips and tricks would you recommend to optimize for semantic SEO?
  
  Thanks!
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  W.E. Jonk: You can markup any page with http://schema.org/WebPage With regard to Google. G supports rich snippets for organisations: ;https://support.google.com/webmasters/answer/146861
  
  With regard to specific HTML5 semantics (for example <article>, <footer>, <header>, <nav> or <section>) and SEO. I don't think it matters at all. ;
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  Greg Baka: Besides schema tags, you could also add the OpenGraph (Facebook) tags and the TwitterCard tags to pages likely to be shared on those social medias.
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  Rommel Badua: +W.E. Jonk and +Greg Baka Thank you for your input, gentlemen! I also keep hearing that there are some 'penalties' or 'black hat' practices that I should stay away from. Would either of you have resources you can point me to?
  
  Is this still valid? ; <meta name="keywords" content="a bunch of key words">
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  W.E. Jonk: The meta keyword is still valid HTML5 since HTML5 is backward compatible, as far as I know.
  
  For SEO the meta keywords doesn't have any value. Google/Bing say they ignore it. However Bing did state that it might be seen as a "spam" signal:
  
  http://searchengineland.com/the-meta-keywords-tag-lives-at-bing-why-only-spammers-should-use-it-96874
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  W.E. Jonk: From the expert panel in this weeks SEO Questions hangout on air on 00:48:20 into the YouTube video: https://dumbseoquestions.com/q/what_tips_and_tricks_would_you_recommend_to_optimize_for_semantic_seo
  
  Reference from the video:
  http://davidamerland.com/
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  Rommel Badua: +W.E. Jonk thanks! That was an insightful hangout!