It really depends.
If you are talking about interested without even you knowing - you
got to have that cute face.
Although certain personalities are seductive and may draw a girl's
interest. (This depends on the person you are talking about and
your own strength)
Astrology mode:
ON
I have a Pisces good friend who is so passive that she will never
initiate a chase, regardless of how interested she is. Although she
is good at inducing interest on the other party.
If one person has more negative energy within her chart, she would
be more passive, comparatively to one with more positive energy.
(It does not mean a girl is more passive, guy are the initiator.
Some guys can't initiate as well) 
Cheers
