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Lighter colors occupy less visual weight, opening up the room. Use glass and thin-legged tables so the eye can see straight through to the floor, making it virtually invisible. Avoid dark stains, woods, or colors as they have a heavy effect, constricting the room.  Design with a cool eye in mind, but adding bright, warmer colors as accents. In general, cooler colors recede, letting the room take center stage -- so that wood floor shouldn't be stained any darker than it already is. Keep the colors to three or less, however; if you're a texture-lover, go monochromatic. It's so easy to think about the square footage of a room and completely forget that there's way more to it than that: just look up. If you can get the eye to move up from the floor, you're good to go. Get a tall, simple floor lamp or vase, full-length curtains, and hang your paintings and mirrors the tall way. This goes for furniture, too. Often streamlined furniture takes up less space but offers all the beauty and comfort of a curved piece. If your room is small, choose furniture that matches. Go for chairs that take up less space (without arms or thinner legs), loveseats, ottomans, etc. At the end of the day, there will be more space in the room. Consider a bench as opposed to a conventional coffee table; but if a table is more you, go for a glass or lucite one. However, too many small objects will make it look cluttered. Just because you have smaller objects doesn't permit you to have more of them. Think of it like dieting -- eating a dozen low-fat Popsicles isn't a good idea, even though they're low-fat. Having a dozen small shelves is furniture overkill. If you have a dark wood floor, this is an especially good idea. A large print carpet, ideally with lines, will open up your space, in addition to brightening it up. It does not have to take up the entirety of your room. Just a large rug that accompanies the main pieces of furniture will accomplish what you're looking for. Start seeing double. An oversized ottoman in the center of the seating area can serve as a coffee table with a decorative tray added, while the piece can also double for extra seating. Or, trade a coffee table for a woven trunk with storage space inside. However, when choosing your tables, opt for ones that have wide open legs. Being able to "see through" the furniture makes the room seem larger to the eye. Select smaller, portable pieces that can be rearranged. Three small end tables grouped as a coffee table are easy to sprinkle around the room to open up traffic flow when entertaining or to clear space for children to play. Utilize the space beneath tables and slide pieces in and out at your leisure. A decorative basket can be seen but still used as storage and taken out when needed.
Choose light colors. Think in lines. Scale down your furniture. Get a large print carpet. Get multifunctional furniture. Choose portable pieces.