First Erotic Spanking - Advice?

Hi all. I'll soon be giving my first erotic spanking (I'm male) to a woman I met from a personal ad. (Yes, we will meet in a public place first, there will be a safeword, we will discuss limits, etc.) While I know a first spanking is going to be no more perfect than the first sexual encounter between two new partners, I'd like to make the experience as good for her as possible.

We have already discussed a role-play scenario, so we are both on the same page about what will happen. My main concern is getting the intensity of the spanking and the duration (spanking and corner time) right. I don't want the spanking to hurt her or the corner time to bore her . . . . well, actually that's EXACTLY what I want, but not beyond her limits. My plan is to alternate several short sets of spanks with corner time so that it is not too intense all at once. I also plan to tell her that I'm going to err on the side of caution, but she can simply say "more" or "harder" and I will oblige (non-safewords such as "no" or "stop" will of course be ignored).

Does this sound reasonable? Anyone have any tips on how to judge when she's had enough or needs more when you've just met?