Installing your own add-ons into Tor Browser is not recommended, as they may bypass Tor or otherwise harm your anonymity and privacy. Check the EFF's Panopticlick to see how trackable your browser configuration is by third parties.

If you're using a Firefox-based browser, you can safeguard your browsing habits and stop advertising companies from tracking you by installing uBlock Origin, Request Policy, and HTTPS Everywhere.

Install NoScript and enable ‘Forbid scripts globally’ to improve the security of your browser by preventing 0-day JavaScript attacks. This is a drastic option as it will render many websites unusable as they rely heavily on JavaScript. NoScript offers a whitelist you can use to selectively enable JavaScript for sites you trust, but this is considered especially bad for your anonymity if you're using NoScript with Tor Browser.

Why is Adblock Plus not recommended? Adblock Plus shows “acceptable ads” by default, which works against the purpose of the add-on. Either disable acceptable ads or use uBlock Origin instead.