You can activate privacy settings on your devices and adjust them to suit your needs. You can customize your privacy settings for apps, operating systems, browsers, online services, social media accounts or search engines.
Your mobile operating system offers you the possibility to transmit diagnostic and usage data to the manufacturer. This can be data for error correction, for example. In addition, operating systems allow you to make settings with regard to personalized advertising.
Activate multi-factor authentication.
Activate only required synchronizations and data transfers (e.g. access to your images by a scanner app).
In your privacy settings, disable the transmission of unnecessary data (such as usage statistics, motion profiles, etc.).
Deactivate push messages if necessary (e.g. profile changes on Facebook).
Disable popular features such as tagging people on other people’s pictures.
Define lists for applications which are allowed to publish messages and which are not.
Allow apps to access your personal information only when absolutely necessary (e.g. access to your calendar or contacts, pictures, etc.).
Minimize (publicly) visible (contact) information.
Restrict access to your social media data to limited groups of friends.
Set the visibility of your profile so that it can only be found by desired people.
Use search engines that do not track your data (e.g. https://duckduckgo.com).