I raised this in another thread but wanted to start another topic on this since I have some more information. Privacy Tools has a great webpage that describes how Firefox users can harden their browser. In my view Ghostery should also have this built in or have an “alt:config” feature if it does not already.
On the topic of extensions, the PrivacyTools web page has a guide (link below) that lists a number of them people can use as well. One other thing that annoyed me was the possibility that FIrefox was still transmitting user’s telemetry to Mozilla despite people electing it not to in the settings. Below is also a link that shows how to see what telemetry is being transmitted and configure the browser to shut that off as well.
Privacy Tools Firefox hardening and extensions guide: