It depends. How often do you manipulate your data? The more data you receive, the more you will need to back up.

For most of us, a weekly backup will be sufficient. If you find that valuable data is being manipulated every day then do a daily backup. The classic schedule involves a backup at the end of each business day, so that’s five backup per week.

The fifth backup each week is saved as a weekly backup and is archived to a fixed medium such as a tape device, DVD, or a separate hard disk which you can keep in a cupboard and not touch rather than being re-used.  If you backup to tape device or hard disk or RW DVDs in the next week. This pattern is continued until the end of the month. The last data backup of the month is likewise stored as a monthly backup archive and no longer touched and the last backup of the year is stored as the yearly backup archive. The total usage break down as follows: Daily – four separate backups (Which you  can use and overwrite each week day, every week, if you wish), Weekly – four backups to archive, Monthly – 11 backup to archive, Yearly – One per year to archive.

 One the upside, you data is backed up off-site which protect you in case of fire, floods and other acts of God. Such services normally offer automatic, timed backup too. One the downside, you may have to pay a fair amount if you require lots of backup space. Some services also ask for a regular subscription. Whatever tools you use, the model of the story is to back up and back up now, don't put it off till tomorrow, it could be too late and your data will be lost! Even if you're short of cash and you need to save up for an external hard disk, use a low-cost blank DVD to start with but get the ball rolling now. Don't put off this task and risk losing your precious data.