Privacy by Compartmentalisation
It was originally used by the Greeks to keep the secret of Greek fire, but now it is used by people all around the world for lots of different reasons.
It can be defined as:
The limiting of access to information to persons or other entities on a need-to-know basis to perform certain tasks.
Think of it as a floor of a house. You have different rooms for different purposes, and you don't mix things up. For example, you wouldn't sleep in the kitchen, nor would you cook in the bedroom. This is a good attitude to have when it comes to privacy.
This guide is going to cover very basic compartmentalistaion. The simplest way to do this is by having 3 compartments:
This should contain everything you use for work, including your email, all of your files/documents (preferably on Libre Office), potentially your LinkedIn and so on...
The best browser for all your needs will probably be FireFox. Maintained by Mozilla, an organisation that genuinely cares about privacy, it is secure and open-source, and, with a few tweaks, can be a great for privacy. You will also be needing a pivacy respecting search engine, such as Qwant.
Next we want a browser for more personal matters such as communitcating with friends or using social media. Our browser of choice is Vivaldi, with Startpage as default search engine. It is also advisable to use the same set of add-ons as you professional browser.
Finally we have other. This is for anything else that doesn't fit into one of the other categories. The best browser for this is Tor. Watching this video and reading this article will help you understand some things you should and should not do on Tor. As for search engine, use DuckDuckGo.
As for operating systems, it entirely depends on your threat model. Compartmentalision, regardless of the operating system, will almost always be an improvement privacy-wise, but if you want to take it further, then any of these will do.
You may be thinking that this all sounds rather complicated, but after a while, like everything, it gets easier. If you are stuck there are lots of great tutorials and sub-reddits on the matter, so don't feel you have to suffer in silence.
I have only touched on this subject very briefly. If you want to go the extra mile, Qubes was an operating system deisgned with compartmentalisation in mind. Snowden, the NSA whistleblower, used it and they even have a sub-reddit dedicated to helping you set it up. The operating systems you should run in your Qubes are up to you, but an example could be Debian for your professional, Ubuntu for personal and have Whonix for other. You can go even further by compartmentalising email accounts, using different adresses (and perhaps even different providers or an email cloaking service) for each service you use.