Firefox is presently the only major web browser that isn't controlled by Google, so it's my preferred browser as someone who hates giant multinational corporations that control everything.
In terms of general use, it's not all that different from other web browsers-- type address or search term in search bar, press enter, click to go, that sort of thing.
Importing data from other browsers
The big thing people worry about when it comes to switching browsers is "will I be able to save my bookmarks, saved logins, and open tabs?" To do this in Firefox, open a Firefox browser window and either press ALT on the keyboard, or right-click in the space where the tabs show up and select "Menu bar". Under File, select "Import from another browser", then find the name of the browser you want to import from and select Next to choose what data you want imported; Cookies, Browsing history, Saved passwords, and Favourites.
Saved. That was easy. Now you can uninstall Brave without remorse.
Add-ons and Extensions.
You've got to use Add-ons and Extensions to get the full experience. All of the add-ons available from Mozilla's website are free and most will safeguard your personal data. If you're familiar with Google Chrome extensions, then there won't be a learning curve.
In a Firefox browser window, type
about:addons
into the search bar. This will open your add-ons settings menu from where you can control, update, and remove add-ons that you have installed, and search for new add-ons. At the very bottom of the page is a button marked "Find more add-ons", which will take you to Mozilla's Firefox Browser Add-ons homepage. Have a look around, see what looks interesting, give it a go. Most add-ons won't require you to restart Firefox, but if they do, the browser will save your history and any website logins to restore your session.
There are a few add-ons I would recommend installing immediately after setting up Firefox for the first time, all are related to privacy (Firefox is already the most secure browser in the world, these just plug any holes that might show up later).
uBlock Origin. Not "uBlock Origin Lite", but "uBlock Origin", full stop. Why is there a "Lite" version of a free plugin? I don't know, but it's not relevant right now. This privacy multi-tool blocks trackers, cookies, and even advertising! If you've ever wanted to experience an ad-free YouTube, uBO is for you. uBO will also prevent content networks from tracking you across the internet. More to that point...
LocalCDN. It's Decentraleyes on steroids. Its sole focus is emulating corporate content delivery networks (CDNs) without actually accessing them, adding an extra layer of privacy as most CDNs are able to personally identify your computer based upon the content it requests. This reduces their ability to profit off your existence while still allowing you to use the internet as normal. It's a large install-- 17 GB-- because it doesn't rely on offsite resources to do its job. That's why it's called "Local" CDN. Everything is carried out on your computer, and nowhere else.
Privacy Badger. Another trackware blocker, made by the Electronic Frontier Foundation. This one is different from uBO in that it can pick up on new trackers that people who make uBO lists may not know about yet, by analysing the behaviour of the website and any scripts it runs. Basically, it does what trackers do, but it does it to the tracker instead of the user. This next one isn't related to privacy, but...
SingleFile. Are you given to datahoarding? Good on you! So am I. If you want to hoard webpages, SingleFile can condense a webpage into a single HTML document for easy storage.
DownThemAll. If you're not interested in downloading the webpage, just the media on the page, DownThemAll can do that. Either you can tell DTA the kinds of files you want to nick from a page, or you can create a download queue by giving DTA the links to things you want to download.
Now, if you're serious about privacy, all of this can take you pretty far, but, it won't protect you against thieves who just straight up steal your computer. As a certifiable paranoid freak, I'm aware that I live in a world full of people who might just walk right up and whisk my laptop away while I'm drinking my coffee. You really should consider not leaving tabs open or staying logged in across multiple sessions. I know there are certain extenuating circumstances; like work or school assignments; but for just general use, consider changing the settings to make Firefox delete your cache automatically when you close the browser.
It's selective; you can tell it what data to delete and what to preserve; but at the very least allow Firefox to log you out of websites when you close it.
"Okay, fine, shut up and tell me how." In the search bar type...
about:preferences
...and navigate to the "Privacy & Security" tab, then scroll down to "Cookies and Site Data" and check the box that says "Delete cookies and site data when Firefox is closed". If you have a website that you want exempted from this rule, such as Tumblr for instance, click "Manage exceptions" and enter Tumblr's URL into the text line, and click "Allow". If you change your mind later, you can delete it from the list.
Next, scroll down to "History" and change it to "Use custom settings for history". If you want to stay logged into websites, retain content settings, or other things that are stored in local cookies instead of on the host server, click "Settings" next to "Clear History when Firefox Closes", and check or uncheck the boxes next to the desired items.
Firefox has loads of built-in customisation options, such as font overrides, light mode and dark mode, and themes, so have a look around.