Just built my new mini up, 2012 i7 quad which I picked up from Amazon as soon as the RAM was confirmed as not user upgradeable. Just added 16GB of Crucial RAM and a 256GB Samsung 850 Pro with a fresh install of Yosemite, so far I'm loving it! If funds allow I'll swap out the HDD for a second SSD.
Then take a look at some install videos. I suggest looking at both for the 2012 because Apple changed some things in some models.