There are some great resources out on the web for backing up and restoring drupal sites. Be sure that you get this configured and running long before you need it. There is nothing worse then needing a backup and not being able to restore it. It could be anything from a module install gone bad, to a server failure.
Here is a great example: backup and restore scripts
The main Drupal site has great resources as well: drupal backup and restore
If you would like to learn more, or just have someone set it up for you, let us know. Contact us here