I wrote about why everyone should learn basic Linux already. This one's more specific — the stuff that would have saved me time if someone had just told me upfront instead of me finding it out the hard way.
You will break your system and that's normal
At some point you'll run a command that breaks your boot, or misconfigure something and lock yourself out, or update something that conflicts with something else. This happens to everyone. It's not a sign you're bad at this. It's genuinely part of the learning process, and it's a big part of why virtual machines and snapshots exist.
Sudo is not a magic "make it work" button
New users tend to sprinkle sudo in front of every command that fails, hoping it fixes permission issues. Sometimes it does. Sometimes it creates a much bigger mess — files owned by root that your normal user can no longer access, permissions that need manual fixing afterwards. Understand why something needs elevated permissions before reaching for sudo automatically.
Distro-hopping teaches you less than staying put
It's tempting to hop between distros constantly looking for the perfect one. You learn more from actually living with one distro through its quirks and fixing real problems on it than from a dozen fresh installs that never got deep enough to hit anything difficult. Pick one, commit for a while, actually learn it.
The man pages are actually good
New users skip man pages assuming they're too dense, and go straight to random blog posts instead. The man pages are usually more accurate and more complete than the blog post, even if they take a bit more effort to parse. man command is worth the extra thirty seconds most of the time.
Package managers are different and that's fine
apt, dnf, pacman — different distros, different tools, similar concepts. Don't expect commands to transfer directly between distros. Learn the package manager for whatever you're actually using rather than trying to force muscle memory from a different one.
Your dotfiles are worth version controlling early
Your shell config, your editor config, all the little customisations — put them in a Git repo from early on. Rebuilding a machine or moving to a new one becomes trivial if your config is already tracked, rather than trying to remember every tweak you made months ago.
The community can be intimidating but usually isn't hostile
Some Linux spaces have a reputation for being harsh to beginners. Most aren't, in my experience — most people remember being new once. Ask questions. Most communities are more welcoming than their reputation suggests.