If you have a "spare" computer -- it can be older (anything from the last 5 years will be no problem; between 5 and 10 years old, your mileage may vary, but then the hardware's so old, it shouldn't be a problem).
Consider swapping in a different hard drive and "preserving" your current drive. That way you can do as many installations of Linux as you want, break it all you want, and you won't jeopardize anything you have on your machine's original drive.
I don't really have any good test hardware anymore, so I just swap drives in and out of my now 2 1/2-year-old laptop when I want to play around with new Linux systems.
I dual-boot Windows and Fedora on my "main" drive, and that's something you can do, too.