Is a firewall really needed ? I though I've read somewhere that most of the
ports are closed by default on GNU/Linux.
Email encryption : totally worth it if the person you intend to communicate
with doesn't have emails hosted at Google and other non-libre services. But I
might be wrong because I don't fully understand email encryption in that kind
of situation.
I also wish to emphasize this : there's no guaranteed 100% complete anonymity
(nor security) at all times. TOR BB isn't excluded from that. Specially since
you must have a different behavior when using TOR (like obviously not
connecting to an online service you've already visited out of the TOR
network, and some less obvious behaviors like waiting to be off TOR to check
whatever you've downloaded).
Btw security is different from privacy. And both can be increased but the
consequence is less convenience. It's a scale between either security or
privacy and convenience.
About the browser plugins : I have a bunch of those. I need to study a bit
more to maybe remove those who're not essential.
decentraleyes
https everywhere
noscript
privacy badger
referrer control
random agent spoofer
request policy (unmaintained I think, I had an issue with the maintained
version and didn't persevere yet)
self-destructing cookies
Ublock origin
Also already mentioned, a VPN is worth it for iproved privacy, but no
anonymity to my incomplete knowledge.