I would recommend getting the binary, or compiling yourself, a Firefox 52 ESR. ESR/Nightly/Dev builds have extra features that regular versions don't. Such as installing non-Mozilla signed apps and more about:config options.
https://www.mozilla.org/en-US/firefox/organizations/
I would also recommend using this doc to mess with your settings in about:config. It's not a comprehensive list (I've yet to be able to spoof my vendor), but it has enough where you can work towards making yourself camouflaged. Using this site
http://kb.mozillazine.org/About:config_entries
You can check more in-depth stats about what your browser is giving off. Like, even if you resize your window, your browser still tells websites your native resolution.
https://browserleaks.com/
And HTML5 canvas is one of the best ways to track you, considering it generates a near-unique signature for users. For this, you should use this and set your settings to "fake readout API" and "constant" for random number generation. This will help blend you in with the rest of the user info. Turning it off is almost as bad as having it on, because that in and of itself is a unique fingerprint.
https://addons.mozilla.org/en-US/firefox/addon/canvasblocker/