Why not use some of her art work on the walls, in different size and style frames (natural, black, white & silver) - you can pick up some cheap frames in the op shop and the bargain stores - just buy some spray paint, and have fun - let your artist help....... you can even photograph some of her art work and have it blown up to poster size - the brighter the better. I'd suggest painting the walls white, with maybe a feature wall a timber bed head - one with a book shelf would be great - a double of course - the room is big enough. A rug to anchor the bed and some funky cushions. An Eames DSW white retro chair and a small white desk with some floating white shelves for odds and ends.... I'd probably get a white roller blind for the window, and paint the door, wardrobe doors and skirtings white, and a lovely large retro style light fitting in the middle of the room, or a hanging pendant next to the bed. A small bedside table - try Ikea - they have a great range, and not too expensive, you may even be able to get a great bedhead there - she sounds a very practical girl, so no frills. You want a young, fresh, modern look. Place the artwork randomly, in groups, on the walls - hang paper cut outs on the walls with blue tack, to see the effect, before you put up the art - Your artist could help with that too. What's her favourite colour??? Does she have any hobbies?? We need photos and more info.... What a lovely step dad you are!!! Good luck. I hope I've helped...

Apart from the paint colour there are a few other things I would change first. Are you able to change the vertical blinds? They are contributing to the dated look. I would lose the table clothes completely and get some modern art for your walls. The lighting is also something I would look at changing especially the ceiling pendant ( too traditional) and the floor lamp. I would also get rid of half the sofa cushions. Changing the paint colour alone will not make your place look modern, IMHO.

I have a lighter carpet now and 3 grandkids that I look after. It's been down 4 years and needs replacing. I had a similar darker carpet and it was down 11 years and survived teenagers and their friends. If you have kids I would go darker every time.

Thank you to everyone who has commented - it is really lovely and so useful to have such thoughtful and encouraging comments! annab1997, the natural white is very yellow against the essastone sample we have, but does seem to work with the ticking. I'm trying a half strength version to see if that works - I also need to try it in the actual kitchen space but can't get in until the weekend (it is a building site). We don't really have any wall space in the kitchen/dining to paint as the wall opposite is full length windows. This provides loads of light to the island, but not much passing through to the back wall of the kitchen. Those small sections we do have - to the right of the bifolds on the picture - will either be in ticking (a great background to some of our artworks) or in the colour we paint the cupboards. I will definitely give the Resene colours a go as well as the Whisper White.