I think one of the most striking things about seeing photographs of true style icons - Audrey Hepburn, Jacqueline Kennedy Onassis etc. - is that they could easily be seen on the streets of any major city in the world TODAY, and they would still look wonderful. There's a lot to be learned from this.
Uniqueness isn't essential - you can easily conform to the current uniform of modern culture and blend in, but that's (1) no fun, and (2) not very chic. You might have to do some thinking in order to figure out who you are, and what you want to convey in your image, but if you want to live an authentic life, your personal image is an important thing to establish and refine.
Walk with some energy. Look interested in your surroundings. Convey some sense of life and engagement with the world around you. Slouching along the streets with a frown on your face won't be chic, no matter what you're wearing.