Probably the most important thing a photographer can do to get great photographs is to make the client relax. She needs to look comfortable and not self conscious about being photographed in her lingerie. The look in her eyes will be key to whether the photograph is amazing or just a picture.
Expect the client to be nervous, as most of them have never done a boudoir shoot before, let alone been seen in their lingerie or less by a stranger. I go through the wardrobe and never allow them to shoot in the favorites to start. I know that the first set will often be the most difficult for them. I want them to be relaxed and ready when we shoot their favorite outfits.
Getting them to relax is a talent and a skill. Treat the client with respect. Provide them privacy during changes. Discuss their concerns about how they look and how they want to make sure is covered. I shoot with a longer lens so I can provide some distance during the shoot. Personal space gets a bit larger when a person is dressed in less, so by not violating this space you can keep them more comfortable.
Some of the nervousness comes from the fear that they won’t be able to do what you need or look bad. Make sure to provide plenty of positive feedback during the photography session. Keep your comments positive, but not sexual. “That’s beautiful” is much better than “You’re making me hot”. The latter will quickly make most clients very uncomfortable. Explain that being nervous is expected and they will be able to create the photographs they want with your help.
Find out who the photographs are being made for and talk about them during the shoot. Ask how they like to see the client. What they like most about the client. If the photographer tones their shoot towards pleasing the future recipient of the photographs, the client will see them as a professional who is working towards creating what is wanted by the client. Thinking about who is getting the photographs also help the client get into the proper mood which will show in their facial expression.
Once the client has become more relaxed you will see the photographs start to take on a whole new look. Your photographs will be better and your client will love you for it. Win-win.