The most important thing on the internet for your Digital Identity and your protection is securing your authentication with the internet, meaning your username and password. If someone is very active on social media, like Facebook, Twitter, or LinkedIn, that page defines him/her professionally, so breaching that page is ultimately breaching the Digital Identity of that person. And the barrier between the attacker and the content is authentication.
Generally, you should now use the same password almost anywhere. The creation of unique passwords per website would be highly recommended, but there would also require that you download some plugin that can store those passwords and remember them for you. So, for example, I have around 200 passwords. There’s no way I could remember them, right? I know some but some of them are truly generic and rely on platforms for me to authenticate into those sites. LastPass•••|
Storing credentials in unencrypted form on a computer, for example in your internet browser, is not the smartest idea on the planet. Probably you should do is use LastPass•••| or find an application, that can store them securely for you and has two-factor authentication.
Two-factor is probably the most secure authentication the general public can get today. Highly recommended. The main reason is that it combines something you have and something you know. What you know is your password, and what you have is usually, for example, a token on your phone. And it’s very hard to break for an average attacker. Storing anything on your device–mobile device or computer–in an unencrypted form that has your private data, either social or private life data is not a good idea.