And most calligraphers are right-handed, simply and only because most people are right-handed.
More on lighting here and here. Some basic issues I'd point out for attention are: 1. If a child has a tendency to be left-handed, forcing her to use the right hand can do her more harm than good.
Experts say that by the primary grades, many left-handed child have not be correctly coached and have developed bad writing habits and experience considerable difficulty as a result. This is really just to make it less likely that they will tear the paper but if they are able to draw those little lines from left to right like righties, it will also help their writing speed and fluency in the long run.
This taught me a lot about the way calligraphic alphabets and techniques have evolved as a function of predominantly right-handers using mostly quill pens for fifteen hundred years or so. I did a bit of research and what follows is what I learned. Unfortunately, a poor grip will often make for problems later on in life, be you a left-handed or right-handed writer, especially when writing those long essays in high school exams.
In practice, left-handers' experience varies. A number of moulded grips are available that can facilitate and reinforce the correct grip, as well as pens with a built-in grip in the barrel.