When hanging art over a mantel or console, measure the vertical space, and hang objects closer to the mantel or console rather than in the exact middle of the space. This will lend a more human scale to the grouping.
When considering a floor plan, start by placing your furniture in the middle of the room and work toward the walls. You'll get a more exciting result.
Be sure to keep your floor plan to scale and be realistic as to what will fit. Don't ask your room or furniture to do more than is possible. This will eliminate unpleasant surprises during installation as well as give the room better traffic flow.
Antique porcelain and books give integrity to a room. Group sets of books and porcelains together to give a more luxurious feel.
Use multiple light sources -- table lamps, floor lamps, art lights, sconces, chandeliers, shelf lights -- for illumination. This enlivens the room, giving it a more flattering glow.
Visually broaden a room by painting the ceiling darker than the walls.
Alter single-socket lamps by replacing them with double sockets. (Be sure to pay attention to wattage specifications.) Use a soft-pink bulb in the socket closest to the seating area and a soft-white bulb in the other one. This provides a pleasing light for your guests' complexions as well as a proper reading light -- both from the same fixture.
Bring balance to any space by using equal amounts of warm and cool colors.
Add more texture by layering accessories of different materials, such as leather, wood, porcelain, silver, tole, lacquer, and crystal.
Use antiques with strong colors, and mix them at will. As the color ages, it acquires a certain patina that makes it work well with a range of other hues. A new piece in the same color, however, will often clash.
Before hanging a mirror on a wall, consider what it will be reflecting and make sure that the object is interesting.
When entering a rectangular-shaped room from the corner of one end, bear in mind that the focal point is the opposite corner rather than the center of the room.
Make a chandelier appear larger by lowering it.
If you are hanging a grouping of art or objects above a piece of furniture with a distinct shape, such as a camelback sofa, allow the grouping to follow the shape of the furniture rather than hanging it in a straight line.
Electrical cords that cannot be hidden, such as those on table lamps, will be less noticeable if they are pulled straight down and tacked to the top of the base molding.
For ease in hanging a group of objects, measure the wall space and designate an area of the same dimensions on the floor. Place the objects within this template and make any desired changes before transferring the grouping to the wall. This is especially important when hanging objects on wallpaper, paneling, or walls that have special paint finishes.