DON'T use an area rug that is too small. Postage stamp-size rugs are one of the most common decorating mistakes. All of the furniture should be sitting on the rug. If this simply isn't possible, the front legs of larger pieces can be on the rug with the back two needn't be. All four legs of smaller pieces should be on the rug.
DON'T choose the paint color first. Paint is available in thousands of colors and can easily be changed. Choose your most expensive pieces first then decorate around them. THEN you can have fun with the wall colors!
DON'T hang chandeliers too high. You want to light up the room, not the ceiling.
DON'T hang artwork too high. People have a tendency to hang art closer to the ceiling than it should be. Artwork should be hung at about eye-level. Obviously this varies from person to person, so use your judgment. But it's better to err on the side of lower rather than higher.
DON'T use short curtains. Curtains and drapes should just skim the floor. It's okay if they're longer and they puddle a bit, but they should never be shorter. Curtains that are too short have the same effect as pants that are too short: they make the wall look truncated and shorter than it is.
DON'T use too many throw pillows. Throw pillows are great decorative accents but don't use so many that you have to move them all of the couch, chair or bed before you sit or lie down. Just because it's displayed that way in a store it doesn't mean the look should be repeated in your home.
DON'T use tiny accent pillows. The throw pillows you use should relate to the piece of furniture. A tiny pillow on a large chair looks bitsy and lost.
DON'T create a theme room. While they can be fun to decorate, people tend to get sick of them really quickly. Theme rooms look old and outdated very quickly and then you're stuck having to spend more money replacing items you no longer want. Instead try to add elements of the theme you like into a regular room. For instance, if you like jungle themes toss in a few animal prints such as zebra print cushions or an ottoman. (This is excluding kids’ rooms!!)
DON'T opt for style over comfort. There are a lot of great looking items out there that look great but are totally uncomfortable to sit in. Always think about how you're going to use the piece before you buy.
DON'T push all the furniture against the walls. Sometimes the room size can make this difficult, but try to pull furniture away from the walls to create more intimate conversation areas. This is particularly important in living rooms and family rooms. Some people are hesitant to show the backs of furniture pieces but if they're finished there's absolutely no reason why this should be so.
DON'T rely on overhead lighting. While it's good to have, it doesn't offer enough lighting, and it's not particularly flattering. It's better to have a mix of overhead, ambient and task lighting. Use table lamps, floor lamps, sconces – whatever you like. Just be sure to use a mix. It will provide more light as well as make the room and everyone in it look better!