The best thing to do is to check your wardrobe. The colours you like and wear often will be most comfortable to you. Blues greens and some yellows are cool colours and many people find them...
If the duvet is a solid red colour you can work with very nearly any colour you like. I would recommend a medium to pastel colour, but let your personal taste help you make your choice. If the duvet...
Bedrooms are intended to be soothing, and quiet rooms. Any pastel shade of your favourite colour will do, remember, the room is yours and should reflect your tastes.