I would probably opt for the slow route myself. I would do something like plan a special evening for her, make an incredible meal, serve some nice wine, and then maybe move to the couch where you can sit at her feet and begin to massage them. Flirt with her in the ways you know she likes and when the moment is right, ask her if she would you to do _______ to her. If she says yes, ask her to tell you what she would like you to do to her. After you've both had a good time, I'd bring it up in conversation the next day. You can tell her how much it turned you on, how much you enjoyed catering to her every whim, and ask her when you can repeat the evening. You can then slowly introduce more elements into your play until you feel comfortable to come out and ask for what you really want.

Good luck.