- Disable DRM.
- Choose “strict” on Browser Privacy. (If it is a good rule in Perl and JS must be good on Firefox also.)
- Tick on “Do not track”.
- Tick on “Delete cookies and site data when Firefox is closed” and press ctrl + alt + supr and delete cookies any time you log or visit any Google, Amazon, Facebook, Apple or Microsoft service when you finish doing whatever you needed of that service or use Multi-Account containers to encapsulate those connections, closing the browser is also an option.
- Install Privacy Badge, NoScript, UBlock and Multi-account containers addons. (You will need to learn to use those.)
- Allow Firefox to send technical and interaction data to Mozilla
- Allow Firefox to make personalized extension recommendations
- Allow Firefox to install and run studies
- Use a dns server which provides encryption and do not store logs.
This should do something to protect your privacy, but it is not a absolute receipt if you really want to protect your privacy must also use your own services or the ones of someone you trust.
If you are not logging anywhere Tor Browser or VPNs may be useful since services can still track you by your IP, but it does not work on all situations, for example if some web only provides a http:// version it can make more dangerous to visit them.
Since you are going probably to end executing untrusted JS sometimes in order to make some webs to work using a properly configured docker container or VM may be useful to avoid a potential Zero Day can break into your computer so easily.
You should also know Firefox provides a profile feature to be able to use different profiles for the different things you do with it.