A thought to all the good stuff already said. Throw out the script. Trying to script a scene in detail before hand seldom works. Even with experienced couples who have spent much quality time together. The problem is that you never know what her or your reaction will be at any given time. Have a few things on the list and pick one as the prinary goal. An example for me might be percussive play as the goal and flogging, paddling, and spanking as some of the things I would do. Then let the scene evolve on its own. If one thing isn't working switch to another path. Don't apologise just move on. That doesnt mean you stick only with one thing. If the flogging is working well you can add a little paddle in to vary the scene before comming back to it.

Also think about pacing of the scene. Think of a roller coaster. The good ones go up and down several times before the end. If you have her worked up to a high platou then back off and give her a little chance to breath and settle before moving on and up. It will add to the amount of time you can scene before she is done and let you take her farther.

Good luck
Play safe