After you initially backup your data files, do incremental backups daily and full backups monthly . This will save you time without sacrificing security. Keep your data in a directory separate from your program files and back up only the data directory. When you save files , do not include any extension and do not put a period on the end of the name. It can be either internal or external and will speed up your backups as well as consume less space than diskettes.
Some files are too big to fit on a single floppy.
If you have a MAC that does not have a backup utility installed on it, the only solution is to obtain one. Some programs do not like to be backed up. You should maintain two sets of backup disks in case one set becomes unusable. If you are doing full and incremental backups on a rotating schedule, do not reuse the last full backups until you have made another set.