"I highly recommend..."
— Brad Vos What They Say

How can I add social sharing buttons to posts?

We recommend using the Jetpack plugin’s Sharing module. It will let you choose which buttons to show beneath your posts. You can choose which post types to show the buttons on (blog post, sermon, event, etc.). Use the smaller JP Sharing plugin if you don’t want to install the whole Jetpack plugin.

You can search for other social sharing plugins to try in the Plugin Directory.