My interpretation of siroco's suggestion was that it was something to try if either your own imagination ran dry or if you were trying to make certain you included a few of her favorite things. In either case I was envisioning this as something that would be done during -- rather than before -- the scene.
(Aside to siroco: not bad...for a slash writer!)
I know a lot of dominants roll their eyes at the mention of safe words, but I think they're essential for first-time tops, because they lack the neccessary sense of proportion that experience brings. Personally, I think even an experienced top should use a safe word system with a beginning bottom (which I guess we've established yours is not), because you never know quite what to expect with a newbie, or exactly how she's going to react to what might be a perfectly innocuous occurance.
I like a two word system, one to mean "time out" and one to mean "it's over". Remember to keep the word(s) easy to remember in a panic, but not something the bottom would normally say. I like "take 5" and "cut", but you can probably come up with something better. I know a lot of people use a color code, "yellow" and "red".
I hope this works out for you, man.