Handguns can be intimidating to a complete beginner trying to get over the fear of injury that comes with handling what can be a deadly tool. After teaching him or her The Fundamental Rules of Gun Safety, it becomes time for the student to learn the operating drill for the particular handgun with which he or she will begin the training cycle. In my opinion, it is unwise to present a new shooter with more than one gun at a time. Ideally, the first gun should be a DA/SA revolver, but that is not always possible. Whatever the selected handgun is, make sure the beginner has a thorough understanding of how the gun works. Then you can move on to using the gun to its full potential.
The business of teaching marksmanship is complex, with many manuals and books written on the subject. For the most part, however, experts agree on the basic principles with the most important being sight alignment, followed closely by trigger control. I have taught these skills to a lot of folks, but never thought of a particular teaching technique until I saw an instructional video a few years ago. It was radical stuff, but it really works.