It can be as complex/simple as you'd like. You could use a bip39 12 word seed with a blank passphrase (13th 'word'), and store thise in your head. But imo you should always add a 13/25th passphrase to make it harder to take your coins if someone stumbles on your 12 words. See this...
https://www.blockplate.com/blogs/blockplate/list-of-bip39-wallets-mnemonic-seed
brash /
npub1ss…wt8u2
2023-05-02 00:30:05
in reply to nevent1q…w8je
Author Public Key
npub1ssttkm353d6jz44g4x99wuqfdugcqw5s5rghvxqqaj2w9hxf5gzqfwt8u2Published at
2023-05-02 00:30:05Event JSON
{
"id": "832fa81b35c4315ce54cd84c500777430c0cbfbbcd073410462f0ede61f08a8d",
"pubkey": "8416bb6e348b752156a8a98a5770096f11803a90a0d1761800ec94e2dcc9a204",
"created_at": 1682987405,
"kind": 1,
"tags": [
[
"e",
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"",
"root"
],
[
"p",
"f5bcf31413c3a5334f2abb5e9e66e4691bd92b6e29a4068e8e9caf550507683d"
]
],
"content": "It can be as complex/simple as you'd like. You could use a bip39 12 word seed with a blank passphrase (13th 'word'), and store thise in your head. But imo you should always add a 13/25th passphrase to make it harder to take your coins if someone stumbles on your 12 words. See this...\n\nhttps://www.blockplate.com/blogs/blockplate/list-of-bip39-wallets-mnemonic-seed ",
"sig": "d83b5398efa9f235a17d6bda1d1d31ca406188f64bbea0d3f20b858016fc1341898b397b95899224175449226e80d698ca15f23fc7219a76f0af2a603359fd29"
}