In spite of hurricane Irma, I’ve managed to upgrade my Mac Mini Server late 2012 with a solid state drive, and then with macOS 10.13 Gold Master. Here is how I accomplished it.

1. Using a USB to SSD/Sata III adapter, I plugged a Samsung EVO 850 SSD into the Mac Mini’s USB port and let the macOS Disk Utility format the drive.
2. Using Carbon Copy Cloner 5, I cloned the original HDD boot drive to the SSD.
3. Using directions from iFixit, swapped the HDD out and the SSD in. I reassembled the Mac Mini and it booted just fine after that.
4. Installed the macOS 10.13 Gold Master (I think).

I wanted to get the new SSD installed into the Mac Mini before the macOS update because I wanted the SSD converted to the new APFS (Apple File System) during the update process, which is only supposed to happen to solid state drives.

The system is running smoothly, and a good deal faster, than it did before. I attribute the majority of the speedup to the SSD. I look forward to this release of macOS, more than any other I’ve worked with so far.