Source an more explanations on how to do that: http://moz.com/blog/meta-data-templates-123
<!-- Update your html tag to include the itemscope and itemtype attributes. -->
<html itemscope itemtype="http://schema.org/Article">
<!-- Place this data between the <head> tags of your website -->
<title>Page Title. Maximum length 60-70 characters</title>
<meta name="description" content="Page description. No longer than 155 characters." />
<!-- Google Authorship and Publisher Markup -->
<link rel="author" href="https://plus.google.com/[Google+_Profile]/posts"/>
<link rel="publisher" href=”https://plus.google.com/[Google+_Page_Profile]"/>
<!-- Schema.org markup for Google+ -->
<meta itemprop="name" content="The Name or Title Here">
<meta itemprop="description" content="This is the page description">
<meta itemprop="image" content="http://www.example.com/image.jpg">
<!-- Twitter Card data -->
<meta name="twitter:card" content="summary_large_image">
<meta name="twitter:site" content="@publisher_handle">
<meta name="twitter:title" content="Page Title">
<meta name="twitter:description" content="Page description less than 200 characters">
<meta name="twitter:creator" content="@author_handle">
<!-- Twitter summary card with large image must be at least 280x150px -->
<meta name="twitter:image:src" content="http://www.example.com/image.html">
<!-- Open Graph data -->
<meta property="og:title" content="Title Here" />
<meta property="og:type" content="article" />
<meta property="og:url" content="http://www.example.com/" />
<meta property="og:image" content="http://example.com/image.jpg" />
<meta property="og:description" content="Description Here" />
<meta property="og:site_name" content="Site Name, i.e. Moz" />
<meta property="article:published_time" content="2013-09-17T05:59:00+01:00" />
<meta property="article:modified_time" content="2013-09-16T19:08:47+01:00" />
<meta property="article:section" content="Article Section" />
<meta property="article:tag" content="Article Tag" />
<meta property="fb:admins" content="Facebook numberic ID" />