You should always take regular backups of your data files. Due to the way the local database works, it is important that Geneious is not accessing the database when a backup is taken. The safest way to make a backup is to use the Backup button in the Geneious menu bar. This will cause Geneious to cease working on the local database and make a zip archive of the entire database, including all preferences and settings. This file should be stored on another drive.
You will need to ensure that the drive you are making the backup to contains sufficient space for your data before you start the backup, otherwise it will fail. The backup will take approximately the same amount of space as your existing Geneious data folder.
To restore a Geneious backup, open Geneious on the computer where you wish to restore it, and go to File->Restore Backup. Note that this will make an entirely new database containing only the backed up data. To add this data to an existing database, please see How do I merge a restored backup with my existing data?
General system backups can also be used as long as these are made when Geneious is in a non-running state. For example, Mac users with Time Machine will have backups taken during the day but if Geneious is running when those backups are taken, they may not be suitable for restoring from as some files may be incompletely copied. Backups taken overnight when Geneious isn’t running would be fine. To load a database backed up with a system or third party backup tool, first transfer the database folder out of the backup drive and into your User directory. Then open Geneious and go to Tools->Preferences and set the data storage location to this database folder.