Sometimes it happens that some friend of mine ask me to help them recover some data they have loss. Recover data is not always easy and often it is very time consuming.
Protect your precious data from any kind of "disaster" is always easyer that recover the data. But to know how to defend your data you have to know what you are defending your data from.
There are many causes of data loss that you can regroup in a limited number of categories.
There are many misconception on data protection, many people put the 1 and 4 category in the sam group, but there are different things for example a fire can destroy your pc and all your backup drives, luckyly this should be less probable that a "simple" hard drive faillure.
Another big misconception is that a raid array is a good backup method. This is just FALSE, a raid array can protect data just from some hw failures (a failure of a power supply can destroy all drive in a raid), A raid array can make a "storage device" faster and/or more reliable, it is an instrument you can successfully use to protect better your data but alone it's just not enought.
Do a frequent backup of all your data on an external storage device (usb pen, dvds, nas...) is always a good solution, but it's not only important what you do bu also how you do it,
Let's make an example :if you replace your all backup files each time you do a backup you could destroy the only good copy of a that was corrupted just before the backup started.
To protect your data avoiding this kind of problems you have to save multiple backup copies in a progressive way, so at a given time you have a certain document produced in different days.
To do that you could just save the backup copy in a folder that have the backup date as a name, most tools are able to do this automatically and can also avoid save a copy of a document if it wasn't changed since last backup (saving space).
Another important thing is to store the backup drive in a different place than your computer, if you keep both your laptop and your backup drive in your bag. a tief could easyly steal both of them