I wish I had the kind of sexy that Lauren Bacall had at age 19 in To Have and Have Not. Apparently the secret of character of Slim was this:
We discovered that she was a little girl who, when she became insolent, became rather attractive. That was the only way you noticed her, because she could do it with a grin. So I said to Bogey, “We are going to try an interesting thing. You are about the most insolent man on the screen and I’m going to make a girl a little more insolent than you are.”
“Well,” he said, “you’re going to have a fat time doing that.” And I said, “No, I’ve got a great advantage because I’m the director. I’ll tell you just one thing: she’s going to walk out on you in every scene.” So as every scene ended, she walked out on him. It was a sex antagonism, that’s what it was, and it made the scenes easy. (Howard Hawkes, via Old Hollywood)
And also a little of this:
I used to tremble from nerves so badly that the only way I could hold my head steady was to lower my chin practically to my chest and look up at Bogie. That was the beginning of The Look. It became my trademark. (Lauren Bacall, via Old Hollywood)
I might also add that lovely low voice and the way Humphrey Bogart looks so amused at her antics. The pairing might have been creepy (Bogart was 45), but instead seems like a perfect match. And it certainly worked out for those two, anyway.