Pastel tones, neutrals and whites “cool” colors tend to give an illusion of more space and a feeling of serenity. Choose bath linens a shade slightly lighter or darker then the walls just enough to make them stand out.
Pare down towels and use just one large lighter floor rug. Select one piece of art instead of lots of small pieces. Use one decorative accessory instead of lots of small ones. Store what you don’t really need out of sight. Less clutter makes a room appear larger.
A large mirror above the sink or collection of mirrors arranged artisitically in the place of one large mirror will open the room up and reflect the light. A wall sconce or counter lamp will bring in a warm feeling and add additional lighting. Also, use ‘whiter’ light bulbs, or select fixtures that are 100w as opposed to 60w. the room will appear larger because it is brighter.