If you are the crazy sort like I am, storytelling is about symbolically integrating the full spectrum of one's personalities into a whole where even the more unpleasant aspects of one's self is understood. I use "Heroine" interchangeably with the term antagonist - the one who starts the action.
The heroine/main character/antagonist has a number of jobs in a story.
First, she is who the audience will identify with. She is the gateway into the story, the one whose motivations and feelings we can understand.
Her second task is to show growth and learning. The heroine is the one who learns the most in the course of the story.
Third, she drives the action, learning how to be in control of her destiny. She takes the most risk of anyone in the story.
She is willing to sacrifice in order to learn or protect. Sacrifice ties in with a death or a death experience. These are often misunderstood as facing a literal death (which is highly effective but can be overplayed). She might let go of cherished beliefs, unbreakable habits, and or a past that holds her back.
From here, you are only limited by your imagination on who this heroine is. She can be a loner, more social, an innocent, orphan, wanderer, waif, or whatever. Once you know her functions in the story, you can write with more passion and confidence.
An adorable sculpture in the Statte Library of Victoria. 
