I take a phrase that I like from a song, book, or movie and then riff on it a bit.
I might start with "God does not play dice with the universe; He plays an ineffable game of His own devising," part of a line from Good Omens.
Then focus down. "ineffableGame" thats a good start.
ineffable Game w/ blank Cards.
ineffable Game for infinite_Steaks
an ineffable Game for infinitesimal 6Steaks
Substitutions of words, puns, plays. It make it personal but you still have a have a hook for remembering it. So long as you follow your own (hopefully somewhat twisted) sensibilities you will have a way to re-derive the password, a sort of logical mnemonic.
Choosing a longer phrase, or a more significant part of a phrase, for more security is a natural extension, and it beats trying to remember complex letter and symbol substitutions. Wordplay is much more natural.