First, check out this post by the always clever Sartorialist: A Less Narrow View. He uses a picture of a woman who does not fit into the established definition of femininity, yet still possesses a distinct and interesting personal style, to show how fashion, in many cases, is about more than just flattering your figure and being on trend.
At the most basic level, we wear clothing as a barrier between our bodies and the outside world - to protect us from the elements and because, well, nudity is not exactly socially acceptable in most places. However, most of us (and I'll assume that if you're reading a fashion blog, you fall into this category) use our wardrobe choices to send out signals about who we are - our opinions, our personalities, and what groups we consider ourselves a part of. For instance, consider a woman who's wearing draped velvet with long, fringey scarves (think Stevie Nicks) versus a woman who is wearing a tailored blazer and trousers - you'd get a vastly different impression of their personalities, wouldn't you?
While most people probably do select clothing that they feel flatters them, in terms of color and silhouette, the image/brand/meaning projected by the clothing is perhaps equally essential. After all, a cable-knit cashmere sweater from J.Crew or Ralph Lauren would probably keep you just as warm as a Rick Owens jacket, but the wearers would probably be two very different women. Same goes for a slinky Versace or Cavalli dress as opposed to an Oscar de la Renta ballgown.
Yes, those examples are kind of obvious, but you probably see my point. Your fashion and clothing choices send out messages - for instance, the girl in the Sartorialist post has a definite boyish, androgynous look - she's not classically feminine or "fashionable", really, but you can tell she chose her clothing with care and it really does speak volumes. To quote one of the commenters, it has an "intellectual appeal" that will catch the eye of like-minded people. After all, people tend to dress in order to show the groups they consider themselves part of, whether it's a man in board shorts and reef flip-flops or a woman in ripped black fishnets and goth makeup. Are these the most flattering looks for them? Depends on who you ask.
So what does your look say about you? Does the impression you create with your clothes match up to the "real you", and do you feel a little off if you're wearing something that just doesn't fit your personality? To quote another Sartorialist commenter, do your clothes "act as a filter" for you?