Excellent guide. The detailed pictures, and the crystal clear instructions, were vital. Used this to upgrade late 2012 MacMini to Crucial SSD. It went very well and took about an hour and a half (I did not want to rush it.)

I did get a little nervous trying to insert the new hard drive. There is a space for drive number 2 and it was a little difficult to get the new SSD into position as it sort of has to "float" in place, above the empty chamber, until the two screws are in place. It took several tries to get this right. (Possibly the instructions should be modified to include attaching the hard drive loosely to the the antenna plate, to assist in placement of the new drive.)

After that, restored OS, all settings, file and apps from old drive. Two hours later, back up and running. Bravo, Apple! With a Windows machine you'll be there for days doing the same thing!