Short hair is sexy. Long hair may look nice, but when it comes down to the act itself, long hair isn't always very practical. It just gets in the way: "Ow! You're lying on my hair! OWW!"
Plus, with long hair comes the increased risk that she spends a lot of time on her hair. Which means she will want to talk about her hair. And you don't want to listen to that.
Short hair is good. Preferably just long enough to be able to give it a good yank.
Instant chemistry is hotter than gradual chemistry. It's funny, thinking about women I've slept with, how often I've known within thirty seconds of meeting them that it was going to happen. Flirting is an activity that I'm quite comfortable with, and a woman who can flirt right off the bat is going to put me at ease immediately.
If you're in a social situation with lots of attractive people about, the first person who flirts with you is often the hottest person you will meet all night. It's about audacity.