Audacity or Looks
someones serotonin, pheromones, bone structure, testoserone, immune system, intelligence, personality and hundreds of other variables all play a part in it.
So all this constitutes audacity and looks and other things.
Depending on what the individual girl is looking for in a man and at what stage in her life she's in and what issues she has. The more of these you tick the more girls just somehow notice you.