Here's how I would do it:
Put SSD in enclosure.
Initialize and format SSD using Disk Utility: GUID and Mac OS X Journaled.
Restart MacMini in Restore Mode; or by holding Alt/Option and selecting Recovery.
Go to Disk Utility when in Recovery or Restore Mode.
Select your HD, perform Repair Permissions + Repair Disk a couple of times.
Select your HD, then Restore; choose your original HD as source and SSD as target.
Once done, select your SSD and also perform Repair Permissions and Repair Disk.
Turn off machine. Swap drives. Et voilà.