Are you guilty of ‘abuse of wallpaper’? Here’s how to avoid it.

Wallpaper is a powerful design tool that can transform a room.

You start with a white box and end up with what feels like an entirely different space, wrapped in an intricate floral design or a bold geometric pattern.

But which one: Intricate or bold? Floral or geometric? With so many colors and patterns available, choosing one can feel almost impossible. And once you do, how do you avoid botching up the installation?

Todd Nickey and Amy Kehoe, of the Los Angeles-based design firm Nickey Kehoe, often wrap rooms in color and pattern, so we asked them for advice. And Nickey, who happened to be wallpapering his own bathroom, invited us along to see how it’s done.

The first step is figuring out where you’re going to hang the wallpaper. Keep in mind: Not all rooms are good candidates for wallpapering.

Smaller, darker spaces like bedrooms, dens, offices and bathrooms — where “you want to feel like you’re enveloped,” Kehoe said — are the best places to hang wallpaper. Larger rooms with great light and beautiful views are often better left alone.

Once you’ve settled on a room, your decisions aren’t over. Where exactly in that room should you hang the paper?

If Nickey and Kehoe are working with a lively pattern in a bedroom, for instance, wallpapering a single wall behind the bed may be enough. Sometimes a visual surprise that doesn’t overwhelm the room is all you need.

Using too much loud wallpaper throughout your home? Nickey has a term for that. “Abuse of wallpaper,” he said, “is a design mistake.”

A better option, he added, is to “punctuate a house with these moments of something really dynamic and let other things fade to the background.”

In his own bathroom, Nickey limited himself to papering the top part of the wall, above the tiled wainscoting.

Another option: wallpapering the ceiling instead of the walls.

Small-scale patterns provide flexibility, but if you have a large-scale pattern, try to make sure the center of that pattern is right where you want it.

“It’s nice if it can line up with the entrance so you’re looking at the feature of the wallpaper in a doorway,” Nickey said.

Similarly, try to avoid placing the roll in such a way that you end up having to use thin scraps of wallpaper in the corners of the room.

Once you know where you’re putting the wallpaper, calculate the number of rolls you’ll need to cover the width of each wall. And make sure to include extra length — known as “overage” — for each strip so the pattern can be lined up and trimmed as needed during installation.

Then add an additional roll to your order.

Wallpaper isn’t a fix for damaged or uneven walls.

If your wall has lumps and bumps, holes or a thick texture, those problems will be visible on the surface of the paper if you don’t correct them before installation. Popped nailheads should be hammered flat, holes should be filled, and textural treatments should be covered with a smooth skim coat of plaster, Kehoe said.

If your wall has many minor imperfections, she added, you may want to use lining paper — blank wallpaper that is installed before the patterned paper — to help smooth things out.

With all the decisions made, it’s time to paste the wallpaper up with adhesive. Nickey and Kehoe usually hire a professional installer, but you can hang the wallpaper yourself if you take the time to keep the paper straight and the seams aligned while trimming it to fit around corners, doors and windows.

Once the wallpaper is hung, don’t be afraid to hang decorative accessories like pictures and drapery. It’s natural to feel nervous about hammering nails or drilling holes into the paper you’ve so carefully installed, but if you want a finished room, there’s no other option.

“Know thyself,” Kehoe said.