HTTPS Everywhere
https://addons.mozilla.org/en-US/firefox/addon/https-everywhere/
Encrypt the web! HTTPS Everywhere is a Firefox extension to protect your communications by enabling HTTPS encryption automatically on sites that are known to support it, even when you type URLs or follow links that omit the https: prefix. Many sites on the web offer some limited support for encryption over HTTPS, but make it difficult to use. For instance, they may default to unencrypted HTTP, or fill encrypted pages with links that go back to the unencrypted site.The HTTPS Everywhere extension fixes these problems by rewriting all requests to these sites to HTTPS.
PrivacyBadger
https://addons.mozilla.org/en-US/firefox/addon/privacy-badger17/
Privacy Badger automatically blocks spying ads and invisible trackers as you browse. It's there to ensure that companies can't track your browsing without your consent. Privacy Badger sends the Do Not Track header with each request and evaluates the likelihood that you are still being tracked. If a domain appears to be tracking you on multiple websites, Privacy Badger automatically blocks your request from being sent to the tracking domain.
Random Agent Spoofer
https://addons.mozilla.org/en-US/firefox/addon/random-agent-spoofer/
Rotates complete browser profiles ( from real browsers / devices ) at a user defined time interval. It includes many extra privacy enhancing options
TrackMeNot
https://addons.mozilla.org/en-US/firefox/addon/trackmenot/
An artware browser add-on to protect privacy in web-search. By issuing randomized queries to common search-engines, TrackMeNot obfuscates your search profile(s) and registers your discontent with surreptitious tracking. Protects users against search data profiling by issuing randomized queries to popular search-engines. Please visit http://cs.nyu.edu/trackmenot/ for a detailed description.