Anyway, this is how I did it. (I'll use a 12 word seed as an example, but I actually did it with a 24 word seed phrase as well. It's a bit harder, but I used the same system I outline below, modified for 24 instead of 12 words).
12 word seed phrase is safe also. Why going for 24 words?
I can advise someone to memorize a 12 words seed phrase but not to fully rely on it but makes it the third or fourth backup. That means 2 or 3 backups must be offline in different locations.