Ming Thein is a well known photographer, though not a fashion photographer. Regardless, it’s good to hear from other excellent photographers working in other fields about the aspects they consider important for good photography. The more types of photography you know and can do the better you will be in your chosen field and what he states in this article still holds for portraiture and fashion shoots.
There are four things to consider in making an image that ‘works’: light, subject, composition and the idea.
Ming goes on to explain these four things in more detail in his article. A recommended short read.