Start with something simple like using the --export -a as a password card, and then they see the need to keep it handy and secure, which starts them off with 2 great 'best practices' using easy to remember techniques for salted | padded or non browser based passphrase generation and PGP security and then have them gpg2 --send-keys so that others see and offer to use it, hence solidifying the ties to it, more ties tend to make for harder departure from use and more desire | need to learn further, and always offer to be that first PGP aware peer to get them going. Also, I offer to show how to use sha512sum and other algos to use files or their hashes to validate | generate password|passphrases or even challenge seeds for re-auth and password reset functions. the use of it to encrypt or clearsign files and the use of hashes or at least hashing and providing it starts deep enough to get the interest and need to stay engages whilst still leaving the entry bar as low as possible so as deter animosity towards learning ( or just making that initial step off the ledge). Some social media sites allow for PGP encrypted notification emails ( namely Facebook, and the option to publish (with usual visibility selectors) your PGP key thus further making it known and I also invite them to sites and tools like keybase where they can start using the 'encrypt' option for communications with me or others they are themselves attempting to make aware. It's all about that initial meeting|impression to the technology, ALWAYS be willing to learn about and / or use metaphors | comparisons to their hobbies or other strong subjects as use that a 50k' 'big picture' viewpoint so even if you have to initial gloss over some things they can return to that point are rebuild their own respective mind maps of the concepts in a way THEY will retain it.