Why YSK: If you have digital data that is important, (family photos, crypto keys/wallets…). Back it up and prevent permanently losing it.
3 different places its saved to, (iPhone, ICloud, laptop, Facebook, Google, Camera SD, Flash drive…).
2 different media, I would consider iPhone and iCloud the same. Buying two External Drives of the same type and brand too. Why? Consider losing your Apple account or the drive model fails in a year.
1 off site copy. If all your copies are in your house, a flood, fire, tornado, hurricane, EMP… would lose every thing.
0 time to waste. (My own personal add). Do it now. Procrastination is dangerous and is the biggest regret for when things go sideways.
Password management is another big topic that is pretty big.
Something as simple a writing it down on paper in a safe location works for some.
https://bitwarden.com/
https://1password.com/
Are also other options.