A room with no windows. Lighter colors – especially yellow-tinted paints and textiles – help reflect the light you’ll need in a room without windows. Painting the trim white and using white or light-colored furniture will also help throw the light around, as will reflective surfaces, such as glass-topped or mirrored furniture and mirrors hung on a wall. And to help “bring the outdoors in,” consider hanging some prints depicting nature. Landscapes and outdoor scenes that include windows and doorways lead the eye outward, creating the illusion of added space and light. And above all, make sure you install top-quality lighting.

A long, rectangular room. To counteract the bowling alley effect of a rectangular space, divide it into functional squares, which are actually easier for the human mind to integrate, says designer Mark McCauley, ASID. How to break up the space? “Use a large plant at the point of demarcation, large artwork, or a bookcase or curio,” he says. These items will divide the space into two halves, each having a separate function; for example, dining room for eating, living room for conversation and TV watching. If you’d rather have the room serve a single function, but you want to give it a more squared-off appearance, paint the two narrower end walls a darker color and the longer walls a light color. This will create the illusion of wider end walls and make the room appear more symmetrical.

Oddly shaped room. You can physically change the proportions of an oddly shaped space with built-ins. Not only can built-ins hide construction errors, but they can serve as interesting focal points while also providing extra storage. To draw attention from a sloping ceiling, uneven floor or a misplaced corner, place a colorful area rug in the center of the room to draw attention away from the periphery and create a central living space.

A low ceiling. Put down a darker floor covering, be it a wooden floor, carpet or tile. Paint the walls with a lighter color than the floor, or use light-colored wallpaper. If you can, use white paint for the ceiling, since this always gives the room maximum light and instantly draws the eyes upward. Hang wall art featuring strong vertical lines, which give the impression of height.