There are interior design rules you should always follow and then there are some you should avoid altogether. Whether it’s because they make a space look out of proportion, too cold, or just overly cluttered, there are certain decorating faux pas that can hinder your space from reaching its full potential.

We tapped two interior designers for the top mistakes they hate to see people make—and how to fix them so you have a space that’s sure to impress.

Ignoring Scale When Buying Items

With online shopping so common now, it’s easy to forget about scale when choosing furniture for your space.

“A piece may look great in a product photo, but once placed in a room, it can appear too small or disproportionate,” says Rashmi Patel, principal designer and founder of RushMeHome Designs. “For example, I often see large walls with tiny mirrors when an oversized mirror would create a more balanced, designer look.”

To avoid this mishap, Patel recommends measuring out your space before adding any items to your cart online.

“If you’re unsure about size, opt for slightly larger pieces—they often make a space feel more cohesive and intentional,” she adds.

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Using the Same Size Decor on Shelves

You may that assume decor items of the same size will naturally go together. However, this doesn’t always result in a cohesive look.

“When styling shelves, it’s easy to fall into the trap of buying variations of what you already love—say, a series of metallic vases—without considering how they interact as a whole,” explains Louis Duncan-He, president and creative director of Louis Duncan-He Designs. “I often see [this]—it looks strange and not natural.”

So, the designer suggests stepping back and thinking about the overall composition.

“Aim for contrast in shape, texture, and material to create a layered, curated look,” Duncan-He says.

Choosing Bulky Seating

Bulky seating can be fun and comforting in the right space—but not when it comes to tight quarters.

“Overcrowding a room with too much furniture or using oversized sectionals in small spaces can make the room feel cramped,” Patel says.

Plus, she notes that it can block natural walkways and disrupt the flow of a space. So, Patel advises leaving enough space for clearance between pieces.

Only Displaying Small Artwork

Large pieces of art can feel like a commitment—and a scary one at that. However, if you’re deciding between something slightly too large or too small, Duncan-He says to always go larger.

“People tend to play it safe, fearing that oversized pieces might overwhelm a space. But nothing disrupts a room’s balance more than artwork that’s too small for the wall,” Duncan-He says. “Going bigger not only feels intentional but also exudes confidence in your design choices.”

Overcrowding Decor

If you’re craving change in your space, you might want to add something new to it. But sometimes, doing the opposite can have a better effect.

Duncan-He references designer Coco Chanel’s famous advice to take one thing off before leaving the home—or in the case of your abode, take one thing out.

“Don’t overdo it—refreshing a room often requires more than just swapping out small decor pieces,” Duncan-He elaborates. “While accessories, like throw cushions, can add charm, sometimes a bolder change—like a wallpapered accent wall—can transform the space in a way that individual items simply can’t.”

Choosing a Rug That’s Too Small

A rug that is too small can make a space feel discordant, or smaller than it actually is—especially if furniture pieces are floating off of it.

“The rug’s size visually defines the room, so if you have a spacious living area but place a small 6′ x 8′ rug in the center, that limited footprint is what people perceive as your actual living space,” he explains.

So, Duncan-He suggests choosing one that’s large enough for at least 30 percent of each furniture piece to rest on.

“It’s a subtle trick that makes your living space feel more expansive,” he notes. “Opting for a larger rug creates a more cohesive, grounded look.”

Overlooking Functionality

We’ve all been there: we see something pretty and we want it. However, there’s more to consider than just aesthetics when decorating your home.

“Many items look great online, but once they arrive, homeowners realize they lack functionality,” Patel says. “For instance, an ottoman might seem like a stylish addition, but if you have a small space, a storage ottoman would be a better choice to store extra blankets or toys.”

This is especially key in small spaces.

“I always recommend choosing furniture with dual functionality to prevent clutter,” Patel says.