Reusing passwords across multiple accounts can make all your accounts vulnerable if one password gets leaked.
Trusting 'secure' websites blindly based on padlock or 'https://' can be risky as it doesn't guarantee trustworthiness.
Ignoring software updates increases the risk of hackers exploiting known vulnerabilities; enabling automatic updates is recommended.
Oversharing personal information on social media can make you vulnerable to targeted attacks; adjust privacy settings accordingly.
Assuming you won't be targeted by cyber attacks is a common mistake; implementing basic protections like strong passwords and two-factor authentication is crucial.