Privacy Guide
These are all personal choices, and I will probably change my mind about some things over time :P
Web Browsing
There are a LOT of choices to make, and a lot of personal opinions flying around. Simplicity is usually better, something that claims to do a LOT of things probably doesn't do those things very well. For example, installing a lot of extensions just makes you more identifiable as someone who uses your unique set of extensions. Even just using two or three extras reduces how much you blend into the crowd.
The only browser extension you need is UBlock Origin. That's all.
As for web browsers, there are few decent choices, depending on how much 'blending in' matters to you, or whether you just want to block ads and have a half decent time on the web.
Firefox
It's better than using Google Chrome! If that's all you're looking for, then it's fine.
Librewolf
Better privacy measures than stock Firefox - more specifically, anti-fingerprinting. Don't tweak the settings unless you are certain you know what you're doing. Don't install extra browser extensions.
Mullvad Browser
My personal favourite: it is identical to the Tor browser, but doesn't run on the Tor network. A lot of convenience is stripped back in favor of privacy (e.g. login sessions are not retained between browser sessions). However, you do not have to be a Mullvad VPN user (though it is recommended for ultimately blending in with majority Mullvad users).
Tor Browser
For ultimate privacy and (potential) anonymity, use the Tor browser on the Tor network. It is not suitable for IRL browsing (such as college/school, banking, government services, etc.), or for logging into most services (such as Google, Amazon, eBay, etc.). The former has the chance of getting you in varying degrees of hassle, and the latter fully jeopardizes your anonymity and renders the entire thing pointless. I recommend a secondary browser for IRL stuff, and a VPN set to your home country for identifiable services (but still not for work or school).
Search Engines
Similar to web browsing, but specifically who you trust with your search history. Google, again, is basically the bad guy in this scenario. Not just from a privacy perspective, but now as I'm seeing from my parents' phones, merely from a user experience perspective too! (Who the hell wants to see trending searches instead of their own history?)
Duck Duck Go
It's a really good and easy switch to make. Excludes all Google results & sponsored results. I find that this is most noticeable when looking for very specific image results, and would usually use Startpage in this case. Other than that, I barely notice any difference.
Startpage
Proxies Google search results, as well as offering a proxy to visit sites themselves. Its "anonymous mode" feature is very useful with the Tor network - if a website blocks Tor IPs, it will very often work when being visited via this proxy mode. This is obviously less private than raw Tor, but a good middleground between usability and privacy.
Searx
A metasearch engine, fetching results from Google, Bing, etc. without sharing search history with these services. It is also possible to run your own personal instance of searx, or use other public instances.