It is a great idea for couples to share their fantasies. From your point of view, you have the chance of living out your fantasies, which is obviously great. You also get the chance to hear her fantasies and have the opportunity to act those out as well. If you are lucky, her fantasies will coincide with yours and then you can both enjoy the situation.
Make sure that the woman is as relaxed as possible, both physically and mentally. This will include putting her mind at ease over what she might want by telling her that you won’t judge her at all on what she wants and fantasizes about. You can also get her physically relaxed by offering her a nice massage. Once she loosens up and loses any tension, she will be more willing to share her intimate ideas.
You have to give to receive. If you want her to be open about her fantasizes, then you have to be open about yours as well. Tell her the things that you are interested in and might like to do, and then ask her what she thinks of them. Try not to go too crazy to start – keep things fun and entertaining for you both and she will probably both be up for whatever you suggest, and start giving suggestions of her own.
Along with being open, you have to be willing to share your thoughts and feelings as well. IF there is something you do not want to do, then it is OK to tell her so. Likewise, there might be something that you want that she doesn’t and you have to understand that no means no. Do not try to push things to far (both figuratively and literally), and do not sulk when you do not get to live out your fantasies. Understand why she doesn’t want to do something and suggest other ideas and ask her to tell you want she really wants instead.