“Not measuring the room correctly, so the furniture doesn’t fit. How to avoid this pitfall? Measure twice, then measure again!” –Joy Moyler, Joy Moyler Interiors

“Don’t measure first. . . eyeballing seems like an easy skill (a skill that Sister Parish had a famously weird ability for). Until you can’t fit a couch through your front door anymore! It’s happened to the best of us. I also recommend coming back to measure a second time; there’s nothing quite like flipping a number or two to really hammer home this point. –Alexa Hampton, founder of Alexa Hampton and director of Mark Hampton Inc.

Bringing in an interior designer too late

“A common mistake in interior design is that people don’t bring in designers early enough in the process. We should be there immediately after you say to yourself, “We are ready to make these changes” or “We want to remodel or redecorate the house”. Often clients contact after buying the house and starting the contractor to renovate the kitchen and bathrooms. A third of the way through to construction, the new owners are overwhelmed with all the decisions they have to make, plus the idea of ​​furnishing afterwards. Contact us when you are in receivership or have closed receivership, and do not start a contractor until you have spoken to a designer first. – Mandy Cheng Design Mandy Cheng

Too small or too big furniture

“Understanding scale is always a challenge, even for seasoned designers. One thing I often see people do is put something really tiny or really massive in a room that inhibits its functionality and dooms its aesthetic. If you know you need a huge sectional for your Super Bowl parties, don’t forget to think about the size of the coffee table and the rug that will come with it. An 8′ x 10′ rug will likely look like a postage stamp associated with most modern sectionals, although it might seem like a reasonable size for the room. (My rule of thumb with rugs and sofas, in particular, is that a sofa should rest entirely on a rug, leaving at least a foot of space on all sides, and rugs should either be centered in a room with at least two-thirds of each padded piece sitting on it, or be a small accent that sits in front of the sofa, with a coffee table on top.)” –Martha Mulholland, Martha Mulholland Interior Design

Choosing aesthetics over comfort

“Not understanding the ‘seat’ of a piece of furniture before buying it. Try going to a showroom and sit/lie down on the padding. If you can’t do this, ask someone to sit down for you to witness how you feel. These are expensive pieces that you want to enjoy comfortably. Try before you buy!” –Alexa Hampton

Poorly hung art

“Hanging art too high. It’s my pet peeve. For some reason, most homeowners think they should hang art up high and so it seems more important. Really, your art should hang at eye level so you can really see the main part of the art well. Also, avoid placing one artwork per wall. It will look very static and uninspiring. –Young huh

Don’t take risks

“In my opinion, the biggest mistake people make is not taking risks. They are afraid to try something new or opt for something they have never seen done before. It’s one thing that makes everyone’s homes look alike. My advice is to take some time before you start, collect pictures and scraps of things you like, test paint colors and look at them at different times of the day in different lights, maybe even in different seasons. And then go! –Frances Merrill, Breathing Design

To be too much maximalist

“Too many patterns, flowers, prints everywhere can disturb the eye. Coco Chanel said, “Before you leave the house, look in the mirror and take one thing off.” I think it can also apply to interior design. –Joy Moyler

Asymmetrical spaces

“A common mistake when designing a room is to disregard symmetry. It creates balance and allows everything to align, from lighting to furniture. To create symmetry, draw a line down the middle of the room and measure to make sure it’s the same on both sides.Then start arranging the furniture from the center line outward. –Nicole Hollis

Accent walls

“Ah, the accent wall. I hate them. (Usually there are always exceptions!) Unless you’re doing clever color blocking like Le Corbusier or decorating an office or restaurant where they make more sense, stay away from accent walls.They feel elusive, restless, and often make the remaining, unadorned walls of the room look sad and forgotten.They can also make a room feel unbalanced. –Martha Mulholland

Skip the underpad

“Don’t use rug pads under rugs and slide into furniture! Every rug should have a rug pad for added safety. They’re cheap and well worth it!” –Joy Moyler

This story originally appeared on vogue.com.