Yellow is a energising, joyful, sunshine colour. It goes well with greys, blues and greens and works well as more of a hint than a block of colour.
Bed sheets, cushions and throws are quick and simple way of adding that hint of yellow to a bedroom.
Re-upholster old chairs and cushions with a fresh yellow patterned or block fabric.
Lighting. Shades or lamps. Big or small.
Furniture. Modern or old. Worn or new. Patterned or block. Mustard or lemon.