Good Firefox addins:

  • uBlock has apparently superceded Adblock plus

https://github.com/gorhill/uBlock

  • Classic theme restorer

https://addons.mozilla.org/En-US/firefox/addon/classicthemerestorer/

  • Flash control

https://addons.mozilla.org/en-us/firefox/addon/flash-control/

  • RequestPolicy – controls cross site requests

https://addons.mozilla.org/en-US/firefox/addon/requestpolicy/

  • HTTPS Everywhere – uses HTTPS where possible automatically on major websites

https://www.eff.org/https-everywhere

  • If you use Plex with Firefox, Transmogrify gives extra options

https://addons.mozilla.org/en-us/firefox/addon/transmogrify-for-plex/