Get to know your subject. Giving your subject a questionnaire prior to your boudoir photo shoot can help her organize her thoughts about the session. Ask her how she envisions the process as well as the final photos. Ask her which of her features she would like to flaunt in her images and which she prefers to downplay. If the subject is a client, then be sure to ask about her plans for the final photos. That will help you create the best possible final product.
Have a face-to-face conversation. I get it, e-mails or texts are easy. However, you want to build trust with your client, and you can't build the trust that you need over e-mail. Even a video conference is an upgrade over text-based communications when it comes to building trust. Take this opportunity to review her questionnaire answers, chat about the wardrobepieces she plans on bringing to her photoshoot, and answer any of her remaining questions (I have clients that come in with notebook pages filled with them!). Your job is to ease her nerves and reaffirm her choice to trust you with photographing her boudoir session.
Make one last call before the big day. The night before her session, phone her again to ask her if she has any last-minute questions. Letting her know that you're excited about her photoshoot will pump her up and further ease any nervousness. Take this moment to also ensure that she knows the location of the shoot and the time that she should arrive.