If you don't have a backup solution for your desktop clients, what is the most effective way to backup users' data, especially their profiles?

If there is no back up software installed or its not connected to an internet. We can tell them to remove the HDD and connect to another PC or laptop with eSATA adapter and just copy paste the files.

Take user profile backup Like

C:\\users\\username

You can use Folder Redirection within Windows environments to protect your profiles and documents.

Activating Windows Schedule backup is the best option

Option 1:If the user is connected to internet they can use Microsoft onedrive to store files in a cloud storage. User can save files up to 1TB.

Option 2:have an archive and then backup files in a external hard drive

My choice would be to use Widnows native backup, which gets saved data to a NAS share.

Other choice would be to create a custom script to zip the user data and save it on a nas share.

It’s very easy to set up a full backup system, though ordinary users may run into problems when the program has filled all the available hard disk space. Some systems may quietly throw away old files to make room for new ones, which means you might not be able to rescue the file you deleted a month or a year ago. Windows 7 periodically creates new full backups, so you can use the “manage space” option in the Backup and Restore control panel to delete an old one.

Windows backup need to be schedule monthly or weekly to be store in one of the shared desktop of server

On workgroup use folder redirection. On Domain use Roaming profiles.

Windows backup will do the job. backup the data to another location or shared folder placed on an alternative server or machine.