Firefox is awesome but it could use a few tweaks to improve the security and privacy. As with ALL browsers don't load up too many plugins and never allow the browser to store your passwords.
This video walks through the settings and has a lot of tweaks done in the about:config area, plus some good suggestions for plugins.
Firefox Privacy Tools and Tweaks
This page How To Guide: Hardening Mozilla Firefox For Privacy & Security 2016 Edition also goes through settings, tweaks on the about page and suggested extensions. Most of the suggestions are the same, but it may be easier to step through the page rather than a video.
The NoScript plugin is tough to manage because there are so many sites that will flag running scripts of some sort. Be ready with some patience util you have it fine-tuned to the sites you browse to.
uBlock is better than Adblock, especially since Adblock has sold-out and whitelists certain ads.