This is something that all single men yearn to know, as they practice the "lines" they'll use when they meet a new woman. But it turns out that it's not so much what you SAY that matters, but your tone of voice when you say it (and there's not much you can do about that).
Women are turned on by low male voices. In the same way that bright plumage attracts female birds, because it denotes a healthy bird, a deep voice may instinctively attract women, because it denotes healthy masculinity (with lots of testosterone).
Not only that, they're more likely to remember what was said to them when it's said in a low voice. In the September 20th edition of the New York Times, Sindya N. Bhanoo quotes psychologist Kevin Allen as saying, "If you want to drop your voice, you should be prepared to be judged by the details that women remember. It could backfire. It's not really a trick that men can play."
Opera has this wrong: In almost all operas, the tenor gets the girl. But backstage, it may be the basso who wins.
And if you "win," should you send her flowers? To get her to remember you, we suggest you send her one of our beautiful crop circle calendars instead. It's a unique gift that she won't find in any store and she'll be able to note your upcoming liaisons on it.