Black walls are dramatic, but they're only as good as what you put against them. The mistake people make is keeping everything in the same dark register — you end up with a cave. Black wants contrast and warmth to actually sing.
Start with your relief colour. A bright off-white reads almost luminous against black, and the higher the LRV the more it pops. Paint & Paper Library Sand I at LRV 95.4 is about as clean and bright as you'll get — gorgeous on ceilings, trim and adjacent walls to give the eye somewhere to rest. Dulux Moon Shimmer at LRV 92.3 does the same job with a touch more softness, which suits north-facing rooms where a stark white can feel cold.
Next, give it a mid-tone to break the binary. Mylands Alderman No.60 at LRV 58.8 is a lovely muted green-grey that sits beautifully alongside black — think panelling, a chimney breast detail, or a piece of furniture. It stops the scheme feeling like a black-and-white photograph and adds a grown-up, layered feel.
Now the bit that actually makes black work: texture and metal. Brass and aged gold are the classic partners — picture frames, lighting, hardware. Warm timber (oak, walnut) and leather pull the warmth up. Without these, black just absorbs light and looks heavy.
"But what about colour?" — black is the ultimate backdrop, so it'll take almost anything bold. Deep reds, ochre yellows and forest greens all look rich against it. Just keep them as accents in soft furnishings rather than competing on the walls.
Practical advice: black eats light, so factor in proper layered lighting — wall lights and lamps, not just a single overhead. And test your black on more than one wall, because a true black and a near-black charcoal behave very differently depending on the light. Mate, paint a big board and live with it a couple of days before you commit.