There are many different kinds of brown – camel, chocolate, burn sienna caramel and so on. However, because black and brown are both considered neutrals, black will really go with any of these browns. Black pants with camel boots and a camel belt, or black skinny jeans with a burnt sienna (kind of a more reddish brown) platform pump and belt will look fabulous. The only thing is, it's very difficult to match shoes with the exact shade in a belt, so they're going to vary from each another. If they're too different (e.g., camel shoes and a chocolate belt), there will be too much going on with the outfit. Try to make the two as similar as possible.
Fabric and Material
Black velour pants with a brown oxford shoe and belt is not acceptable. But toothpick black denim ankle pants with a brown oxford shoe and skinny belt can be beautiful. Fabric and material are so important when it comes to this color combo. Upscale-looking fabrics like denim, suede, and leather, for instance, are going to look much better than cotton, velvet, and synthetic.
The Top Half
Almost everything will go with trendy black pants and a set of fashionable pumps, boots, or stilettos - like a fitted cashmere sweater, loose modal tank, or a chiffon button down shirt. But the top half of your outfit has to match the bottom half, color-wise. Because black and brown are basic colors, go for the same color scheme up top, as opposed to donning bright green or yellow with your black pants and brown belt/shoes combo, try a soft blush pink, cream, or a gray.
Putting together an outfit is all about harmonizing. There are endless rules about how to combine pieces of clothing, but when it comes down to something looking good, it's all about how the end result looks as a whole. Although black pants with a brown belt and shoes does work for the most part, always check the mirror to see how it looks all together. If something's off (like the shoe, the belt, or the shirt), change it up, experiment. If it's on, walk out that door and strut your stuff.