SSH: Best Practices

Are you using SSH in the best way possible? Have you configured it to be as limited and secure as possible? The goal of this document is to kick in the new year with some best practices for SSH: why you should use them, how to set them up, and how to verify that they are in place.

All of the examples below assume that you are using EnGarde Secure Linux but any modern Linux distribution will do just fine since, as far as I know, everybody ships OpenSSH.