The thing nobody tells you about black shoes is that black doesn't stay black. Cheap uppers go grey and slightly green within a few months, the sole edge turns a dusty brown before the leather does, and suddenly the pair that looked sharp in the shop looks tired next to a plain black trouser. It still matters to have a proper pair, because almost nothing else in a wardrobe gets worn against so many different outfits without a second thought, but it's worth knowing that the colour itself is the part most likely to let you down first.
A good pair tells you early, before you've even walked anywhere. Proper leather or a dense suede has a bit of give and a slight sheen that doesn't look like it was sprayed on, whereas the disappointing version is stiff, flat and a bit shiny in the wrong places, like it's wearing a coat of varnish. Turn the shoe over and look at the stitching round the sole, not just whether it's glued, because glued soles are fine for a while but they're the first thing to peel at the toe after a wet week. Buckles and eyelets should feel like metal, not like plastic painted to look like metal, and they should sit flush rather than catching on tights.
Where black shoes genuinely do a job is in the bits of a wardrobe that aren't meant to shout. Dark denim, grey trousers, a navy coat, anything camel, they all sit next to black shoes without a fight, which isn't something you can say for most other colours. I wear mine with tailored trousers for anything that needs to look a bit put together, and with a plain dress when I can't decide what else is right, because black shoes rarely are the wrong decision even when everything else in the outfit is a compromise.
If you're starting from nothing, go for a low block heel or a proper flat loafer before anything with a thin heel or a strap, because those two cover formal and casual without asking you to think about it every morning. A pointed court looks lovely in the box and is the one I'd leave for later, once you know how much walking your day actually involves.
Buy black shoes true to your usual size and never a half size up hoping leather will stretch evenly, because it never stretches where you need it to.