If you're stood there holding a black boot, the first thing I'd ask is where the zip sits and whether you can actually get it over your calf without lying on the bed to do it up. Black boots are the one bit of footwear almost everyone owns, but the fit round the ankle and calf is where most of mine have let me down over the years. A boot that gapes at the top looks sloppy under trousers and lets all the cold air in, and one that's too snug will cut a line across your leg by mid afternoon. Check you can bend your knee properly in the shop, not just stand there admiring them in the mirror, because that's the test that matters once you're walking rather than posing.
Black boots don't love being paired with anything too fussy underneath. Thick textured tights with a lot going on, or a hem that's a slightly warmer black, can look oddly mismatched once you're outside in daylight rather than under shop lighting. I'd also be careful mixing a very shiny patent boot with anything else shiny on the same outfit, it starts to look like you got dressed in a hurry near a disco ball. A matte or slightly textured finish is far easier to live with day to day, it goes with more and hides scuffs better than high shine, which shows every scrape within a fortnight of normal wear.
Mine age well if I actually look after them, which I don't always manage. A suede pair I wore through one whole fairly wet autumn went patchy at the toe because I never bothered with a protector spray before the first proper downpour, and by December they looked like they'd been dragged behind a car. Leather ones are more forgiving, a wipe down and a bit of polish every few weeks keeps them looking decent, and they soften and mould to your foot in a way that actually improves with wear rather than wrecking them. Stuff them with paper when they're wet rather than leaving them to dry near a radiator, that's the bit I always forget until the leather's gone stiff and cracked at the crease.
Where they're the wrong choice is anywhere genuinely smart in a formal, old fashioned sense, a black boot still reads as casual to some eyes no matter how polished, and they're no good for standing all day on hard flooring without proper cushioning, your feet will remind you by four o'clock. For most ordinary days, work, weekends, the school run, an evening out, they're the thing I reach for without even thinking about it.