I saw this thing on TV where they did all these interviews for jobs with different people for the same position.
But they didnt tell the interviewer that they were sending one of the same people in twice, once with curly hair, once with straight.
They said curly was distracting, more likley to hire the one with straight hair after interviewing all of them.
And then they showed a bunch of guys a bunch of pictures of girls (and did the same thing with the interviewers, two pics of the same girl mixed in with the other girls one time with straight hair and the other time with curly) and they said that the one with straight hair was hotter.
But if your going for flirty, curly is the way to go.