If you attach the seed words (12 words in my case) to a story and memorize it, it is unlikely to forget it. Then from time to time, tell the story to yourself, let's say when you go to sleep (instead of sheep counting).
As a backup, I use multisignature backups (2 out of 3) stored on my phone/home pc/work laptop. What would be the chanches to forget my seed and 2 of my backups to get destroyed at the same time.