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Different forms of second factor.
Two hardware devices, so you can store a backup safely in safe.
Enable two-factor authentication wherever you can, but make sure you have a back-up mechanism in case you lose your device(s).
Option of 2FA — so if you do make a mistake and give away your username and password, still hard for someone to make use of them, as they require an extra piece of data which (hopefully) on your can generate.
Downside of 2FA is that, if you lose your device, you may well be locked out of your accounts.
If the second code is delivered over SMS, you can probably get a new SIM, get your provider to move your number across to the new SIM, and you are up and running.
If you use an app — which means you are not reliant on getting an SMS — you may struggle more. I don’t have a great solution for this at the moment.