Paint the walls of the room with a flat or eggshell sheen latex paint. Choose a light color -- such as a neutral beige, light gray, soft green or cool blue -- to make the room feel larger. A light color on the walls is more reflective of both natural and incandescent light, giving an open and airy feel. Avoid dark colors that will absorb the light and cramp the space.
Paint the trim and all the woodwork white. Apply a white or light colored latex glossy paint to all trim pieces in the room with a high-quality paintbrush. The light trim will make the walls seem farther back and give the illusion of a larger space.
Choose bare floors to increase the size of the room and decrease the size of the couch. Remove the carpet if you have a hardwood or laminate floor underneath, since carpeted flooring or large rugs can make a room appear smaller.
Place the couch against a wall to avoid crowding the center of the room. This will allow the walkway to remain unobstructed and provide a natural flow to the room.
Consider glass tables instead of wood. Adding a glass end table or coffee table allows for light to flow through and creates an open feeling. Choose round or oval tables if the couch is rectangular with hard lines, while square tables work well to offset a curvy, oversized sofa.
Hang sheer window coverings. Sheer or light fabric panels allow more natural light into room to make the area appear larger. Pull back the panels to receive the most light.
Hang a large mirror in an area where it will reflect natural light or a unique piece of artwork. The mirror will expand the depth of the room and help to visually shrink the size of the couch.
Include thoughtful decorative elements, being careful not to add clutter. An excessive amount of pictures or keepsakes in a room will create chaos and make an already large couch seem bigger.