It is essential that any photographer builds up a portfolio of their work, this is what will bring in new clients and help make or break a reputation in any particular field.
This is the same for a professional photographer looking to specialize in nude pictures, as any other genre.
A good place to start is at the local classes on art and in particular the drawings of still life.
This helps in understanding the human form and all its different curves and what poses are worth pursuing. The subject must always feel comfortable so it is worth working on your interaction with models.
Looking to the existing experts in the field is very beneficial, these professionals have been doing it for many years and there is much that can be learnt by examining their work. The lighting they use, camera angles and other photography techniques are all there to be tried out and turned into your very own.
A busy photographer is always looking at ways to improve his skills, new body shapes to embrace, new more innovative ways to use the lens and get the very best out of a subject. The world of glamour modeling is a good enough place to start and there is always a high demand for this sort of work.
Eventually you will want to create more of your own style and be recognized as someone offering something very different. That is the way to get noticed in the commercial sense and if you are lucky you could end up making a pretty good income from your passion.