There's no substitute for good communication. I know it isn't necessarily "sexy" to discuss this with your clothes on, but it's entirely necessary to do so. There will always be opportunities for spontaneity, trial and error. Sometimes, even the best-laid plans will fall flat. It doesn't mean you give up on everything. Learn from it and move on. It may be helpful to print out a BDSM checklist to find out what she's most interested in. Then you can surprise her with an activity she wants to try.