Too many functions in one room. A room with a futon, a desk, an exercise bicycle and a sewing machine is difficult to read and looks jumbled. Limit the use of each room in your home to one or two activities.
If you have a desk in your family room and another in your den, why not combine the two in one location? Disguise the desk in your bedroom as a vanity by adding perfume bottles and a pedestal mirror and store your office supplies in decorative containers. Or, hide your work station with a folding screen. In a multi-use room, create distinct zones for each purpose.
An awkward furniture arrangement. Don't block or constrict the traffic flow. Use the furniture to guide people into or around groupings. Group your furniture in vignettes and conversation areas. Avoid lining up the furniture against the walls (unless it's a child's room). Don't leave uncomfortable air holes — you'll feel more at ease if that blank space gets filled with furniture, even if it never gets used.
Lack of cohesive style. Pick a theme or concept you like and use it throughout the space. Clearly define the overall look and feel you want in the room and write it down. Let's say you want your living room to be "light, airy, informal and country." Placing a sleek, chrome-legged coffee table next to a frilly, flowered couch will not create a harmonious effect. You don't have to select perfectly matching pieces or even ones of the same period or in the same style. Combine pieces that relate and harmonize with each other because of shared design elements such as color, scale or repeated motifs and rely on your own gut feeling about their emotional relatedness to your design concept.
No color scheme. A room random color — a red couch here, a toothpaste-blue chair there and an orange rug throughout — can be difficult to spend time in. Consciously select one, two or three colors to highlight in each room. (Treat a multi-colored pattern as a unit or one "color.") Make the eye take in the room as a whole by carefully placing the colors in your scheme throughout the room. If one part of the room lacks color, place a colorful accessory in that area.
Poor lighting. It's annoying to strain to see the faces of your guests, or to be blasted by an interrogation-like spotlight. Don't rely on standard ceiling lights to provide sufficient illumination. Supply ambient light by installing wall sconces, or sitting torchères in the room's corners or by strategically placing table lamps throughout the room. Eliminate heavy light-blocking window treatments, add a mirror or two, or invest in a skylight to increase natural light.
No focal point. On entering a room, your eye scans the space and searches for a center of interest. Create a focal point to keep the eye from flitting about and build your furniture arrangement around it. In the bedroom hang a strong piece of art, a kimono, a hat collection or a kite over the bed. In the bathroom, place a vase of flowers and a figurine on the countertop to divert the eye from the toilet. If your living room has no fireplace, create a symmetrical furniture arrangement on one wall for an altar-like effect.
Too much clutter. Too many knick-knacks, stacks of papers and piles of books can spoil the effect of even the most beautifully appointed room. If you can't eliminate the clutter, at least corral it: Reserve one room in the house, or one area per room for clutter, leaving cleared surfaces everywhere else. For example, pick one drawer in the kitchen for loose papers, hang all family photos in the den or hallway, and place all collections in an etagere or bookcase.
Random accessorization. Display art and accessories that have personal meaning for you and that enhance the look, feel and theme of the room. Hang art so that it relates in color and feel to nearby furnishings. Keep the art of proper scale: One large piece of art or a series of smaller pieces work better over a sofa than one tiny piece. Group accessories in odd clusters, rather than lining them up. A few carefully chosen pieces have much more impact than a dozen meaningless trinkets.