The mistake most people make is going full nursery-cliché — bright red, electric blue, sunshine yellow. Looks cheerful in the tin, but those saturated brights bounce off the walls and wind kids up at exactly the moment you want them winding down. You want calm, soft and a bit grown-up — a colour they won't be embarrassed by at ten.
For little ones, Earthborn is my first shout. It's clay-based, breathable, virtually no nasty VOCs, and the muted nursery palette is gorgeous — soft greens, dusty pinks and gentle blues that photograph beautifully and feel restful. The Claypaint finish is genuinely lovely.
If you want something with a touch more depth, Little Greene French Grey - Pale is a soft sage-grey-green that suits a boy's or girl's room equally and ages well. Their paint is low-VOC and the colours have real character without shouting.
For a warm, cocooning girl's room, Farrow & Ball Setting Plaster is a soft pink with enough warmth to feel cosy rather than saccharine — far more sophisticated than a typical "baby pink".
And if you want a calming blue, COAT Lie-in or a soft mid-blue gives a restful sky feel without going stark. COAT is water-based, low odour and dries quick, which matters when you're trying to get a room back in use.
The "but what about a feature wall?" — fine, but resist the temptation to do a wild colour. Better to paint three walls soft and one wall a slightly deeper version of the same family. Or save the personality for removable stuff: wall stickers, bunting, framed prints. Kids' tastes change every eighteen months — your paintwork shouldn't have to.
Practical bit: use a washable matt or eggshell, not flat matt — sticky fingers and felt-tip happen. And always go for a low-VOC, child-safe formulation. Earthborn and the supported eco ranges are your friends here.