What is the ideal way to restore a previous version of a site with Backup & Migrate files?
You can restore using backup &amp; migrate itself.

If you've backup and downloaded the file, then you can use Restore tab (/admin/config/system/backup_migrate/restore) to upload the zipped file and restore.

If you've backed up to the Manual Backups Directory, then you can restore from the directory listing (/admin/config/system/backup_migrate/destination/list/files/manual).

There are Drush commands for the above as well, see drush help after you enabled backup &amp; migrate module.