Use large expanses of mirrors sparingly, if at all, in rooms where you spend a great deal of time.

Mirrors can be terribly distracting. When you sit across from a mirror or a mirrored wall at a dining table, you're tempted to constantly check your image on the opposite wall, rather than concentrate on your dinner partner. On the other hand, mirrors can be space stretchers in transitional spaces like entries and halls. A full height mirror on a wall at right angles to the front door, for example, can enlarge it visually - and allow you to check your appearance when entering or departing.

A mirror at one end of a long hall can reflect the passage of people and fill otherwise empty space. If you have a bright color on one wall of the hall, as well, the reflection of this color in the mirror will help enormously to shorten the space. In living rooms, however, mirrors should be used sparingly and only where they will be helpful in extending or consolidating spaces.

In a small living room I designed, for example, two windows on either side of a narrow section of wall made the space seem choppy and busy. I covered the 3-by-5-foot, conventional-shaped windows with vertical blinds in white. Covering them from the ceiling to the floor gave them new proportions and a feeling of stature to the room. To unite the separated windows and to give a feeling of spaciousness to the small space, I mirrored the face of the wall between the two windows as well as the two projecting sides of this wall space.

What does this do for the room? First of all, by reflecting the vertical blinds the two windows reveal, the space between the two windows seems almost to disappear and to become a part of the windows themselves, in the process making the entire wall seem wider.

Secondly, the mirror reflects what is essentially a serene and simple space, a typical conversation group of modular units upholstered in white and grouped in front of the windows. Behind the larger unit is a Parsons' panel end table for a lamp and books. On the wall at a right angle to the windows is a simple storage wall, built in to maximize the usable space, and finished in white to make it part of the wall. Reflecting this serene grouping adds to the feeling of spaciousness in the room. If the furniture or accessories were sharply accented or overly patterned, the reflection in the mirror would have made the room seem smaller simply because there was too much happening in the reflection.

In this room, however, the glass top of the coffee table, the neatly arranged books and stereo equipment in the storage wall, a few, but important, live plants, and a great bowlful of brilliant flowers are reflected in center stage, projecting a quiet but dramatic center for the room.

In another similar living room, I used a mirror at the corner to give continuity to a different kind of space. Here, a ribbon of window covered two of the four walls. At the corner itself, a hefty column not only blocked a fabulous view but also looked like a rude interruption for the vertical louvered window covering I used. By mirroring both projecting faces of the corner itself, I made this corner disappear. It reflects the vertical blinds when they are drawn, looking as if they simply continued around the corner. And the mirror also reflects the view, by day and night, further extending, the feeling of space and the outdoors into the room.