If you have landed on the radar and become a target of dedicated and/or technically sophisticated actors, such as criminal organizations, government agencies, foreign nation states, or from actors such as stalkers, jealous significant others, or family members who may have physical access to your devices, the game of protecting your privacy changes entirely. With specific attention directed at you, these types of actors are not simply trying to collect and monetize your data in wide drag nets, they’re focusing efforts on you specifically and you will need an approach customized to you and your situation.
In the case of governments or cyber criminals targeting you, they commonly use phishing, social engineering, and/or the use of technical vulnerabilities to plant malware or key logging software in order to gain more access to you and your data, though there are a wide range of tactics that can be employed. In the cases where the threat actor may have physical access to your electronic devices, they can potentially plant hardware or software in them to track your location or log your keystrokes to gain access to your online accounts. If an actor gains access to your online accounts, such as banking or email, a lot of information about you, your location, and your activity can be ascertained. In some cases, simply sending an email to the account of one of these actors can potentially allow them to infer information, such as your location depending on timestamp or time zones in emails in conjunction with other information, such as your address or the address of someone you know.
With these sorts of actors, the situation is usually unique or nearly so, based on your technology, your habits, and your online footprint. To successfully protect your privacy against these types of actors, you must have a deeper understanding of the technology that you use and you will almost certainly need expert help. Some of the principles in protecting yourself lie in understanding how technology can be used against you and being very disciplined in what technology you use, where you use it, and how you use it. This can also extend to technology beyond your own, to include that of friends, family, and people you come into contact with. This can also mean opting out of using certain technology entirely. Consultations and help from security and privacy experts can help you understand the risks you face in your personal situation, with the technology you use, and how you can deal with them.
As a few examples of tactics you may need to employ to protect yourself from an actor targeting you, you may need to use cash or privacy-focused cryptocurrency for some or all of your financial transactions, leave your phone in a faraday bag and only take it out and use it in temporary and controlled locations, and/or connect to the internet and use your online accounts from anonymous or public locations (still through a VPN).