Before you do anything else, make copies of all your system's boot diskettes. DOS diskcopy may work in case you lack another Unix box on which to run dd . These boot diskettes will be your lifeline if anything happens to your root file system. As soon as you have done the bulk of the installation, including the installation of optional packages, make a backup. Each time you make significant changes to the system's configuration and have proven it to be stable, make a backup.
Tape outstrips even CD-ROM for restore speed.
When you create these safety backups, use cpio or some other tool that archives device nodes as well as regular files. If your system dies on you, reinstall only enough of the operating system to get the tape device working. Then do a complete restore from tape, remembering to specify the overwrite parameter to your restore tool. Paranoid system administrators frequently draw chuckles from their more laid-back colleagues. But the sysadmin who invests the time to create a workable disaster plan will reap the rewards of that effort.