Make a 'System Image' of all partitions on the main HDD. Save to the external 1TB.
Macrium Reflect Free is widely considered as very good for this (actually I'd say the best)
Macrium also allows you to Create Rescue Media.
Actually a CD/DVD or an iso file to burn to USB Flash.
When you get a problem, you boot from Rescue Media and restore partitions from the Image file on the ext drive to the main drive partition slot.
Keep original Image and make additional ones regularly.
eg weekly, fortnightly etc.
When you get too many, just delete superseded ones.
There's also another app 'Easeus Todo Backup Free' which is perhaps a little more user-friendly.
It's much slower but does do Incremental and File and Folder Backups as well.
It needs it's own boot media too, which it will create, or it can put an entry in the Windows boot loader (Pre-OS)
Images can also be Mounted with these apps to allow Restore of just a few individual files or folders, if desired.