Make sure you get a ton of sleep the 3 days leading up.
On the day of.... Make sure you go out to the gym or a run and really sweat it out. To clear the mind.
Remember that you are not an open book. Mystery is good. Only you can control your conversation. She will be just as nervous as you. If she offers any crumbs. Do not take them.
She needs to see that you are not an option, which I believe is part of your boundary.
Flowers always make people better, happier, and more helpful; they are sunshine, food and medicine for the soul. unconditional love is awesome!