If you’re loooking for a bit of light reading before bed, this might be just the answer: An Advanced Introduction to GnuPG.
Sleep tight!
On a mostly related note, I’m going to move all of my (admittedly trivial) secure e-mail to my ProtonMail account. If you have any reason to contact me securely, I advise you e-mail with GPG at gmobrien at protonmail dot com as of December 2018.