uBlockOrigin
This extension is something that every FireFox installation should have, it blocks not only annoying ads and trackers, but also you can set it up to protect yourself from malicious domains.
Here are some custom filter lists I use with it:
FMHY Unsafe sites filterlist - Plus, ClearURLs for uBo (unofficial), LegitimateURLShortener
Violentmonkey
A userscript manager for the sites, it's really usefull if you get some interesting scripts or make your own
Here below are some scripts I use with it:
Undiscord, Vencord, Bypass All Shortlinks Debloated
Stylus
Extension lets you overwrite the stylesheet of the sites, I have been using it for now only to debloat discord client from nitro and shop nonsense:
Disblock
SponsorBlock
The extension let you skip the sponsors and other fragments of YouTube videos, it works on Invidious instances and it is quite good!
PrivacySpy
It let you see the ratings of privacy policy made by the sites.
Behind The Overlay
It lets you quickly remove the overlay popups from the sites that blocks you from reading the article!