This guide mostly covers traditional hacking and surveillance risks as commonly imagined, but the most frequent case of illicit access to data is actually through phishing and social engineering, causing the victim to willingly give their password to their attacker.
Social engineering (social hacking) is a wide range of real-world strategies based on social interactions and impersonation aiming to obtain access to accounts or services such as payment, physical access to locations or other privileges. This can include pretending to be new colleagues, distant authorities, or relatives of co-workers.
Social hacking is one reason why security questions are not safe, and you should avoid replying to them. People can find information about your first pet's name, your mother's maiden name, your favourite food or city, etc. over conversations, social media, and viral posts/questionnaires asking for such information.
If security questions are required by a service you are using, you should lie rather than give information someone else could research, and remember your lies. You can consider this a secondary password field rather than an actual question.
Be wary of any social media posts where you are asked to share personal data, such as "Pay tribute to your first pet" or "What would your fantasy name be based on your date of birth?" and do not participate. These are exploited to answer security questions and get access to your accounts.