If you only do one thing do this! Set-up 2 Step Authentication
Two-step authentication – the most important thing you can do to stay safer!
We recommend setting up two-step authentication on all accounts that allow you to do so. Two-step authentication is an extra security measure that your iCloud, Google and Microsoft offer. It is also available on apps like Facebook, Twitter and other online services.
2 Step Authentication adds another level of protection so if your abuser tries to access your account they won't be able to even if they do know your username and password.
It works because it recgonises whenever you log in from an unknown device or want to change account settings, it will ask you for an extra security code/PIN which is sent via email or mobile. We recommend you use your mobile so you receive it in a text message. Some allow you to add an alternative mobile in case yours is lost. In this case, we recommend that you choose a trusted friend or family member as the second mobile.
The advantage of using two-step authentication/verification is that if someone does get your password and are trying to access your account they can't do so without the PIN. It's like having to log in twice.