I tried writing this yesterday, but I encountered an error when I tried to upload a picture. Beta. Anyway, it was probably too long winded.
In short, when people ask for advice about what to wear, it seems they aren't often sure what exactly what it is they want to look like. My stock answer is always: find 15-30 pictures of outfits you like you like, what really speaks to you. Don't think too hard about why you like it; just find and collect those examples. After you do, look at them all together and try to draw out common themes. Those themes likely are a very good representation of your style preferences.
I like this approach because it, to a large degree prevents our preconceptions of what we think we should wear from influencing our understanding of a unified style (or styles) that speak to us.
Of course, just because a person is able to discover his style in this manner, that doesn't mean he can successfully execute it. That requires an understanding of why the pieces work together to create the effect that he finds so appealing. But it is a necessary first step.
Alright. I'm going to try posting an example in a separate reply. This is where it crashed last time.