Contrary to what others write*: Yes, the terminal.

It’s not that you can’t get by without it on many distros, for most things. But for even for medium and non-techy users, getting the fear of the terminal out of the way early will make their journey much, much smoother. It doesn’t have to be much, no shell scripting or anything, just the basics, conceptually what a terminal is, what the shell is, how to execute stuff, maybe chmod +x to execute, other utilities like ls, cp, mv, mkdir. maybe symlinks/ln. That’ll be enough to take away the fear if they see any “Now do this in the terminal” advice online (which they absolutely will, let’s not delude ourselves), and maybe enough to get them to notice that “huh, sometimes the terminal is more convenient, they weren’t bullshitting when they said that”.

*) Since you asked about “beginner Linux users” and not users that “just want to use their computer and not think about the OS at all”, I’m pretty confident about that assertion.

PS: I really think that’s not too much too ask. I remember my mother learning DOS commands back in the day for a regular desk-job. Everyone can do this, it’s not difficult, people just have to let go of a few false preconceptions drilled into them by the industry (MS, Google and Apple).

The biggest “Linux” skill would be package management. It is one of the biggest differences.

Most of the rest of the advice here stems from desktop environment choice.

Trusted sources, only.

Same as Windows, Android: sideloading (tarballs, flatpaks, snaps whatever) is a no-no.

Like bash curl install.sh bad

This thread is largely just basic computer skills advice that is necessary on Windows and Mac as well. (And that is great!)

So I’ll add the ones we skipped that have nothing to do with OS at all, but are the usual issues for new PC users:

• Give a quick overview of what the mouse is for.
• Talk about or just disable the CAPSLOCK key.
• Show them where to find and how to read the “do I have Internet?” icon (usually in the lower right, regardless of OS)
• (If not a laptop) Teach them that the monitor and the PC have separate power buttons. Maybe leave a sign out that says “Push both buttons to turn on.”

And as others have said:

• Show them how to search for and add software using the software center, (rather than download from random websites)

Little quality of life stuff.

• How to install video codecs
• How to get thumbnails working in the file manager.
• Adding cloud storage to the file manager.
• How to make libre office save files with MS office filetypes by default (depending on work / school requirements)
• Maybe samba shares if they have another computer in the house.

For truly casual users (grandma or a student taking notes) there isn’t a lot to learn. Here’s your browser, here’s your office apps, this is like “notepad”. This is the software center for updates or any other applications, press the “windows key” to get your menu.

Rtfm. That problem? it’s almost always a permission issue.

That it is another OS. It’s not Windows.

There is no recycle bin. Double-check before deleting files.

It’s not just for Linux but :

• there is an error message somewhere

It’s fundamental because instead of saying “It doesn’t work!” and get no useful help, people must think of it as an investigation (or whatever get them going) looking for clues. Until you get the right message and can provide the right context (e.g. what computer are you using, what OS version, etc) then you get generic help which is like looking for a needle in a haystack. Sure it’s not entirely impossible if you are both lucky and patient but you are doing yourself and others a huge disservice.

Before Linux maybe they were used to black boxes but here, nobody is intentionally trying to hide away anything from you!

PS: bonus, notes are basically free. Jolt down notes about anything and everything you are learning. Don’t just “use” a computer, LEARN how to use a computer.

I find that one of the biggest differences is the file ownership/group design, and the non admin user. Sure, it might not come up in a straightforward manner, but it will.

Why do I need to put in a password all the time? How come I can’t just move this file to another drive?

This might be too “advanced” for what you’re looking for, but I think even basic usage comes across this.

I set up Mint for a non-techy relative on their old desktop.

• Their use-case is almost entirely web browser, so there was no need to cover installing programs. Click the same browser icon and it should behave basically the same way.
• No need to explain the terminal beyond “this is where you can type advanced commands, you don’t need to worry about it”.
• If there’s an error message, read it and try to understand what it’s actually saying rather than just dismissing it. Do a web search if you’re feeling confident, send me a photo of the screen if you’re not.
• Explain how to install updates (or just configure automatic backups and updates for them).
• Explain when and why the computer will ask for a password (e.g. login and updates) and how that password is for the computer, not for their email or whatever.
• Explain the basics of folders. This is your home directory, here’s where downloads go, here’s how to create a folder and drag your files into it.
• Tell them not to panic. I’ve seen a lot of older people terrified of pressing the wrong button, make sure they know how to understand what they’re doing and undo their mistakes.
• Be patient!

DO NOT download and install random programs from the internet. Not a deb/rpm file, not an elf binary, not an install script, nothing. Use your package manager or desktop environment’s app store. At most use flatpak or snap packages.

Linux gets its reputation for not getting malware from the same place Mac does: It has a managed app repository where you get all your software from. Difference is Mac doesn’t let you install arbitrary programs at all, while Linux expects you to know better than to do that. Someone who doesn’t know what they’re doing downloading Linux programs from random websites will inevitably hit one of the super rare Linux malware in the wild.

Even ignoring security issues, running an install script even from a reputable open source project’s website can open you up to package dependency hell. And if you ever need to upgrade or modify it, you’re in for a rough time because none of the existing tools built into your distro will help you. It’s even worse than Windows when this happens because Windows at least expects for things like this to happen (because everything comes in its own installer and handles updates separately) and has UX elements to help non tech savvy users deal with their mess of apps, Linux expects anyone bypassing the normal package manager to know what they’re doing and if you don’t, it won’t be a good day for you.

googling and copypasting in that black app called terminal

The bottom level of your file system is /, not C:, and other drives or partitions you have will be represented in subfolders like mnt or something.

Everything is represented as a file, even things that are not strictly speaking a file on your primary hard drive.

The part that you interact with the most, your graphical user interface, has a particular name, like gnome, kde, xfce, icewm, etc.

When you have to open a terminal, you might be interacting with different shells as well, but it will usually be bash.

Always install from the repos unless your nerdy friend who helped you get set up says it’s okay to download this or that particular app.

Maybe include a bit about how to run regular backups automatically.

And also list out different alternative programs relative to what they might be used to in a Microsoft environment.

One thing that many guides tend to skip is how to install software. People coming from Windows might try to install software the “Windows way” by going to the website and downloading them. That is just likely to cause pain and suffering for a number of reasons.

Instead, every beginner friendly distro has its own flavour of software centre that users should be encouraged to use instead. Maybe even include a link to flathub in the guide or something.