Something we see on the internet from time to time is guys shooting in what they fondly imagine to be the fashion style. The hire a model, get some clothes together, some lights, and off they go. They chuck the model in a defunct factory, or in an alley, because they usually haven't got a mansion or a Rolls-Royce, and the results are... well, they're not that good, often.
The following is my theory of fashion. I don't shoot fashion, because it's hard. There's probably other ways to do it. By looking at a lot of pictures, I have devised this, though, and you might find it interesting or helpful.
A picture can mean almost anything, it can try to convey any sort of feeling or idea. In fashion, there's only one idea: The model looks fantastic, and these clothes and accessories would make you look fantastic as well. Sexy, wealthy, put together. A picture that conveys nothing, or conveys something else, it might be excellent but it ain't fashion.
In any picture, if the model is in an alley, the picture has to sell us a reason for her to be there. Or possibly you're just doing some Dada shit. Most of the time, we're looking for some sort of a reason, some reason to believe that her presence in the alley makes some sort of sense. If this is to be fashion, there is exactly one reason that model can be in that alley: Because it makes her look fabulous and put together.
Look at any fashion photograph. The hallmark is that the photographer appears to be in total control of the frame. There is literally nothing in the frame that doesn't work, that does not fit. There's almost always a very strict color scheme in play: a set of colors form a palette of similar hues, saturations, and values, together with a complementary palette. The bricks behind her, her hair, the purse, and her shoes are all one palette that's complementary to the color of the dress. There's usually strict design, the lines do the leading thing. There are repeated textures and patterns throughout. The tiles echo the pattern of the dress, the puddle echoes the line of the purse strap, and so on.
Sometimes the colors are quite fake, almost always saturation and hue have been selectively adjusted (once you start looking for it), the lights have been gelled for the shoot, and so on. Total control and management of the frame, before and after the exposure.
The reason the model is in the alley is because the brickwork sets off her hair perfectly. The reason she is in the defunct factory is because the graffiti on the broken machine behind her perfectly echoes the drape of her dress; the peeling green paint on the walls completes the palette of colors started by her purse, shoes, and the necklace; and because the bright splash of indigo paint spilled on the floor is the exact color of her dress. Pro tip: The graffiti that matches the drape of the dress was put there by you, as was the indigo paint, and then you adjusted them in photoshop to be exact.
The reason the model is there was created by styling. It is this styling that creates the sense of total mastery of the frame. The frame is perfectly, totally, controlled, because that skillful control is what makes the model and the clothes look incredible.
If you don't hit all the notes pretty much spot on, it's just a girl in an alley, looking lost, stupid, and out of place.