Traditionally, someone who doesn't care what anybody else thinks, or at least pretends to.
If she sees something she likes in Urban Outfitters or Topshop, she'll get it. If she sees something she likes in Abercrombie, she'll get it. If she likes something in a thrift store, she'll get it, etc.
Likewise, her music taste should be what she likes, not limited by any sort of genre.
She will read, write or draw if those are the things she enjoys or is good at.
SHE WON'T ACTIVELY TRY TO BE DIFFERENT, SHE JUST IS! To be an indie girl, you have to be someone who is mature enough to know who you are and happy enough in yourself to stand out.
To be a fake indie girl, however, you need only 4 things. Tumblr, photoshop, a pretentious jumped-up attitude and a fringe.
Fake indie girls are the ones who google 'bands that nobody has heard of' to make themselves different.
Fake Indie- Check out my Tumblr with photoshopped pictures of beaches with writing! Or don't, but that's just because you're jealous of me and my cool indie-ness.
Indie Girl- No, I'm alright doing my own thing.