The must meta tags for your website to appear on Google search, Google+, Facebook, Twitter, Pinterest: rich snippets.
Wnat your webiste to appear og google search with rich snippets like the one below, use structured data, SEO tags, Twitter cards and open graph protocol (enables any web page to become a rich object in a social graph).
SEO Tags
Up to 70 Characters of Keyword-relevant to your website text here
Google+ Tags
Open Graph tags - used by Facebook and also by Google search
Twitter Cards - will show rich text when someone will tweet your URL. You can specify website and app types of cards.
Here is the example for Twitter card for Twitter Auto DM (sending DM automaticaly to a new followers on Twitter) from vicconsult.com
You can refer to Pinterest developer page for rich pins guide.
The example below shows recipe rich pin example on Pinterest for thecookingtale.com - delicious cooking recipes:
