First and foremost, find out how he/she learns best so that any future instruction will be geared towards that learning style.
Next is the idea of Start Well, Finish well. Teaching them posture, grip, etc for setup. Then teach them where you want the finish to be. These two things are of primary importance and are the EASIEST parts of the swing to analyze since they are the only static points in the swing.. and thusly we can be as critical as we want of them.
Next comes the recognition of how to become aware of movement. Recognizing when something is happening and not trying to change it, but simply make the mind aware of it. Once you have the ability to do that specific things during the swing can be covered.