Dude, do as I said. You have to appear pre-selected by other females - it drives competition. Even if it's a female friend. Also, gauge her self-esteem. If it's low, lay eazy on the teasing and disqualifications; if it's high, that will draw her in.
Availability is non-attractive, not pre-cognitively, but sub-cognitively. We did not evolve into apex creatures by choosing the most feeble, most obviously unselected mates. We evolved to apex status via dominance competitions for female mating; and therein, females choosing which males posed the highest possibility for survival, and successive reproduction of the most dominant genes.
If you're pre-selected, you have good genes; if you're perpetually available, you obviously don't.
Like I said, desperate dudes compliment. Forget her number deliberately, and tell her you had a million other things on your mind; you can maybe meet her at 'X' social congregation on 'X' day, though. Show up with another woman (totally plutonic) and fain interest in your target's friends. All sounds stupid, but it works.