That's smart -- when all is working well, definitely make a Windows system image backup. I make one after each new OS Build (quality update) comes in, & I keep the last three. By renaming the computername folder in the WindowsImageBackup folder, the images are kept separate & distinct, & all three will be offered at the time one needs to be restored...
Each is a backup of all the Windows partitions required to boot & run Windows: EFI, MSR, Windows (C:), & Recovery. If you've got additional partition(s), they will also be offered for inclusion.
Make it at "START, Settings, Update & Security, Backup, Go to backup & Restore (Win 7), Create a system image". Afterward, make the Repair Disc or ask Cortana for Recovery Drive to put it on USB. Then see...
How to restore a Windows 10 system image to an existing or larger storage device
https://www.winhelp.us/restore-a-system-image-in-windows-7.html
Restore a System Image Backup in Windows 7, 8, 8.1 and 10
Note: That is an informative 3rd-party site, but I know nothing (good or bad) about any downloads or links that are there (or anywhere else).
If your external hard drive (or the internal one I guess) is a Seagate or Maxtor, there will be a free version of Acronis True Image at their site. Seagate calls it DiscWizard. Macrium Reflect, AOMEI Backupper & others also offer free versions of their image makers. These 3rd-party apps are quicker, make more compact images, & are more flexible in use. But the Windows version works in under 15 minutes on my small & uncomplicated system. I must add, DiscWizard's Bootable Media (to restore an image when Windows won't boot) requires a Mouse to operate. Plug one in, & it is instantly recognized.