I wish PGP was easier to use. When it comes to having to invoke gpg directly I usually spend some time with the man page and that’s enough. But when it comes to the more detailed stuff like setting algorithm preference or identities I always fall back to the collective internet knowledge. I think I’ve looked up the following links a few times now and I’m leaving them here for reference:

https://wiki.debian.org/Subkeys
https://www.debian-administration.org/users/dkg/weblog/48
http://blog.infertux.com/2013/11/03/how-to-remove-an-email-address-from-a-gpg-key/