but be careful. You should install a disk that's freshly formatted. It shouldn't have anything written on it. You should first format, then install, and finally copy stuff. You also need the S drawer and the startup-sequence if you don't already know just in case.
This is incorrect information you are giving. The disk does NOT have to be freshly formatted nor have any data on it; the disk can be completely full with precious data and installing a boot block (with the command Install Df0:) on it will not cause any data loss whatsoever! You are confusing an AmigaDOS disk with a NonDOS disk (like games with custom loaders) which by installing a boot block on it will render the disk completely inop.