I use the negative space as a friend. I have extra things like trash,boards,cars,dumpsters and walls with graffiti to detract from the negative space. I try to go for a real looking scenes so i look at everyday life and see how the negative space is filled. for the back drops i use a big poster board i painted one in black for night and forest shots and one in sky blue for day shots. those were best. Cropping yours shots like someone else said tends to work to. I try to shoot the shot perfectly without using ps. i still use it for some shots but i tend to not use it as much anymore. hope this helps take a look at some of my shots so you can see how i fill the negative space! cheers and happy shooting!

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"All things are subject to interpretation whichever interpretation prevails at a given time is a function of power and not truth. "
Friedrich Nietzsche