Credit to http://pjrvs.com/ - saving this for later.

wordpress-sharing-meta-tags.php

<?php if(is_single() || is_page()) { ?>
  <meta name="twitter:card" content="summary">
	<meta name="twitter:site" content="TWITTER_USERNAME">
	<meta name="twitter:creator" content="TWITTER_USERNAME">
	<meta name="twitter:url" content="<?php the_permalink(); ?>">
	<meta name="twitter:title" content="<?php the_title(); ?>">
	<meta name="twitter:description" content="<?php the_excerpt_rss(); ?>">
	<?php if (has_post_thumbnail()) { ?>
	    <meta name="twitter:image" content="<?php the_post_thumbnail(); ?>">
	<?php } ?>
	<meta property="og:type" content="article">
	<meta property="og:title" content="<?php the_title(); ?>">
	<meta property="og:url" content="<?php the_permalink(); ?>">
	<meta property="og:description" content="<?php the_excerpt_rss(); ?>">
	<meta property="og:site_name" content="<?php bloginfo('name'); ?>">">
	<?php if (has_post_thumbnail()) { ?>
	    <meta property="og:image" content="<?php the_post_thumbnail(); ?>">
	<?php } ?>
<?php } ?>