1. Use a long, strong and unique password for each of your accounts (see HowSecureIsMyPassword.net)
2. Use a secure password manager, to encrypt, store and fill credentials, such as BitWarden or KeePass / KeePassXC
3. Enable 2-Factor authentication where available, and use an authenticator app or hardware token
4. When you enable multi-factor authentication, you will usually be given several codes that you can use if your 2FA method is lost, broken or unavailable. You could store them in your password manager or on paper in a safe place so you will not be locked out
5. Sign up for breach alerts (with Firefox Monitor or HaveIBeenPwned), and update passwords of compromised accounts