We are moving soon to a very old house, while specious and relatively light, third bedroom DD's room is the smallest, long and tad narrow it also has the smallest window, hence it is dark I don't know what to do with it. My starting point is pair of lovely soft yellow Maris Laura Ashley curtains, My question, is Can I also paint the walls in yellow? Or should I go for something else? Which colours do work with yellow? Furniture in her bedroom will be white, light coloured carpet, white metal daybed with yellow bedding? I can't afford to get it wrong. TIA DD is 6, so it can be grown up/not too whimsical.
I think soft grey or green in a dark room risks it looking cold.
I would paint the walls in a yellow several shades paler than the curtains - effectively an almost-white with a tinge of the same colour as the curtains.
If the walls are very uneven you could also consider using a lime paint or something like that with a colourwash in a few different shades - has the advantage that if you don't like the effect you just add another layer, and each layer makes it more complex and beautiful.