I've struggled when trying to teach others basic guitar (most probably due to impatience) but I've learned a whole lot just about teaching by viewing the tutorials on this site.
Anders Mouridtzen also has a great style of teaching... In fact, all of the various tutors I've checked out so far on this site are great.
I would say start with using the Guitar Fundamentals 1 and 2 courses. Its UBER basic, but its gives a wonderful foundation from the get go.