Bip39. Entropy values have to be sourced from a robust source of randomness. What this means is flipping a fair coin, rolling a fair dice, noise measurements etc. Do NOT use phrases from guides, lyrics from music, your birthday or steet address, keyboard mashing, or just about anything you think https://thetopdirectory.com/listings13054024/bip39-passphrase-generator-https-linktr-ee-bip39-facts-about-bip39-standard-revealed