For anything that can be >20 characters I use easily remembered sentences complete with punctuation/capitalisation/etc.
eg. Not one I use but a question I was asked that has stuck in my head for >30 years

Passphrase:
Does cam low profile alter valve train component acceleration?For anything <20 characters, I use
Password Card as mentioned
here, kudos to joby_toss btw.
I have a pair of these laminated back to back, after using a password, (selected off them), a few times, I no longer need the card to look it up but it is there if I need it.
If I need something ridiculously complex, (ie. hard to remember), I'll take something easy to remember and ROT13 or ROT47 it, (or
ROTxx).