Getting started (short version)

It is recommended to read the long version, but you should be fine if you just do the following:

• First, and foremost: Be prepared that nothing works as you would expect, especially if you consider yourself a power user. Linux does not try to copy Windows. Stuff works differently. Your knowledge of regedit and powershell is useless, you will not be able to troubleshoot issues the way you're used to, and your favorite software to do something might not be available. Think of it like being dropped back to level 1 in an MMO. It's like that. There will be issues, and you will have no clue what to do. Imagine installing Windows and your performance being bad. You obviously would install the GPU drivers. Now imagine you would use Windows for the first time, and you have to figure out what the fuck is wrong. Be prepared for this. It will happen, and it will happen more than once. The good thing is, that you will learn everything much faster than someone who has no previous knowledge. But keep in mind that you have years of experience with Windows, and absolutely no knowledge of how to use Linux. Don't expect to know how to do everything, and be prepared to put time and effort into learning stuff. You will probably think that Linux is more complicated than Windows, just keep going, and you'll get to the point where you'll think the opposite. But it will take time.
• Don't immediately remove Windows, try dual booting, or try installing Linux on a laptop first. Give yourself some time to adapt. The beginning will probably not be easy. It's always good to have a fallback if things don't work as expected. You can remove Windows later, if you're sure that you don't need a backup solution.
• Your experience will be much better if you have supported hardware. Your RGB keyboard may not blink in the way you want it to blink. You might not be able to change your mouse DPI or lift-of-distance. At least not out of the box and not without hassle, or without bugs. Wifi and Bluetooth are also known to be problematic. Check if your model is supported, or get a supported model. If you have a laptop that is unsupported, not all features will work out of the box, or might not work at all or without bugs. Normal functionality of other components is usually unproblematic, you should not have to worry about your CPU, RAM, etc.
• Not all games work. Check protondb.com for information about what games are currently working on Steam. You can find other games on appdb.winehq.org. Most games that don't use anti-cheat work, even if they are not listed. However, they might not work without tweaking.
• Use Nobara. It will make less problems, and gives you better performance than most other distributions.
• Use the Official or Gnome version if you want something easy that works.
• Use the KDE Plasma version if you want customization, a little bit less input lag, and you can live with something a little bit more complicated.
• Depending on your computer, it might be necessary to disable "secure boot". That might sound scary, but fear not. Your system doesn't get insecure if you disable it. Secure boot is a technique that secures that only systems signed by Microsoft can be booted. Since most Linux distributions are not made by Microsoft, they're also not signed by them.
• Use Steam for running games that are on Steam. Most games will work just like that, after enabling Steam Play for all games.
• Use Lutris for all other games.

• Disable Composition: Your games will run like shit if you don't disable it.

• If your performance is bad, read this article.

• Don't go to a website and download stuff to install it. This is not how Linux works. Even if this is the "official" way. For example AMD will offer you to download their drivers from the website. Don't do it, this is bad, and it will probably break your system!

• If you use the terminal, Linux will usually not protect you from shooting yourself in the foot. Instead, it will deliver the bullet in the most efficient way possible. If Linux actually warns you that you might be doing something stupid, take it seriously. It's not your average "You could harm your computer" bullshit you are used to from Windows.

• Error messages also have a meaning. They tell you what the problem is. Always include them when asking for help.

• You (almost) never download software or drivers in the browser. Doing this is a really bad idea, and should only be your last resort if everything else fails. Just look up your distribution + the software, and you should find a better solution. You shouldn't need to do this on Nobara, everything should already be ready.

• If you don't like the look, it can easily be changed. Just install a different desktop environment. KDE Plasma would be a popular choice that looks a lot like Windows, is very customizable, and very comfortable to use.

• Expect that you're going to reinstall your system a couple times while getting accustomed to it. Linux comes without training wheels, or double bottom. At the same time, it invites experimentation, and if you don't know what you're doing, this can lead to a broken system relatively quickly. So always back up your important data! But fear not, after you learned how your system works, it won't break that much anymore.