Keep your private keys secret. Assume everything else is public information.

Everything will be breached, hacked, leaked. Keep that in mind when registering on sites/apps, and what personal info you input in those.

Use fake info whenever you can. And use e-mail aliases, it's a easy way to know if some service got breached. Or just don't use any BTC related service that still requires e-mail/passwords in 2024.