Last year, Tracy McCubbin — who has been a professional declutterer for two decades and lives by the motto “don’t put it down, put it away” — married a man she described as “very messy.”

Both acknowledged the “cosmic joke” of their unlikely pairing. Ms. McCubbin put blue painter’s tape on every drawer and cupboard in the kitchen when the pair first moved in together, offering a map to what goes where. But she has also learned to practice what she preaches to her clients, staying cool and calm about messes that don’t affect her day-to-day functioning. Like his night stand, which is buried under books, charging cables and remotes to TVs she is fairly certain they no longer own.

Or the jumble of tools her husband, an avid gardener, tends to leave in the yard. “It’s all over the place,” Ms. McCubbin sighed. “But you know what? We have a beautiful garden. Our fruit trees are fruiting. It’s really been about understanding: This part doesn’t matter.”

Ms. McCubbin, and other experts in organizing as well as psychology, said there were a few practical strategies that could help pack rats and neatniks cohabitate in relative harmony.

Improve your organization systems.

“Oftentimes when one person is more cluttered, the underlying thesis is that they’re wrong, that they’re doing it the wrong way, that they’re bad,” Ms. McCubbin said. But in many cases, household clutter is simply an indication you don’t have solid systems in place.

Some of the solutions she offers to clients are almost too obvious, she said. For instance, she has worked with frustrated parents whose children toss backpacks and coats in what she calls the “landing strip” just inside the front door. Hanging a few hooks that they can easily reach helps.

Ms. McCubbin also recommends adding sufficient shelving for an avid reader’s books. (“The line in the sand is they have to be on a shelf. They can’t be in stacks on the floor.”) At home, she put a dish by the front door, so her husband wasn’t “losing his mind for 10 or 15 minutes every day” looking for his wallet and keys.

“It’s always important to explain that these systems are being put in place to help,” she said, “not because ‘you’re wrong.’”

Focus on functionality.

Ms. McCubbin said it’s most important to consider the practical implications of clutter.

“The goal in getting organized is to make your home work for you,” she said. “It’s not about rainbow bookshelves or making things look perfect, it’s about getting control of clutter so that you can cook in your kitchen and actually use your garage.”

Pour most of your energy into common spaces, Ms. McCubbin advises her clients. For example, she and her husband like to cook, so the kitchen must function well for both of them, she said. But he has an office and a bathroom that she rarely steps foot in so she does not have to see the mess. (Many people don’t have that much space, she acknowledged.)

Focusing on function can be especially helpful for parents who don’t want to battle their children over messy bedrooms. Antonia Colins, who runs the website Balance Through Simplicity, has two adolescent daughters, one of whom struggles with neatness. So Ms. Colins has set basic ground rules, she said. For instance, she insists on clutter-free floors and a desk that is clear enough to study from. (She also expects her daughters to put their dirty laundry next to the washing machine, and return any plates or glasses to the kitchen.) But she looks the other way if the bed isn’t made perfectly or if there is a pile of clean clothes in the corner.

Consider the deeper issues at play.

Sometimes clutter piles up because someone is unwilling to put in the effort to clean and organize. Other times, it is because they have mental or physical roadblocks, explained Michael A. Tompkins, a psychologist and co-author of “Digging Out: Helping Your Loved One Manage Clutter, Hoarding and Compulsive Acquiring.”

Perhaps the most obvious example is hoarding disorder, but there are other links between mental health and messiness. For instance, those with attention deficit hyperactivity disorder (A.D.H.D.) or other executive functioning issues often struggle with excess clutter. In those instances, patience and understanding can go a long way, he said.

Physical limitations can also be a factor. “I’m 73, so I can speak to this personally,” Dr. Tompkins said. “My ability to maintain my living environment has degraded as my physical capacity has degraded, not because I’m not still interested in keeping my living environment tidy and organized.”

He said that it is important to note any sudden or drastic changes in a person’s household cleanliness (or if they seem to be accumulating an unhealthy amount of stuff) and flag them to a primary care physician, as they can indicate an underlying health issue.

If a person is simply unwilling to compromise on clutter, that may also be cause for concern. There could be more foundational relationship problems at play.

“It’s never just about the socks,” said Kiaundra Jackson, a licensed marriage and family therapist in Los Angeles. “It’s really about poor communication skills, or other needs, or gender roles — or something way deeper.”

If one person in the household is especially rigid about clutter, that may be more about control than cleanliness, she said, and is something he or she may need to work on in individual therapy. Couples therapy or simply working with an organizer can also help you come to a better understanding if you have reached a stalemate, Ms. Jackson said.

Be strategic in how you talk about it.

Though outside support can help, learning new communication tactics can sometimes be enough to defuse conflict, Ms. Jackson said. Don’t broach the topic of clutter when anyone involved is hungry or tired, she said. And beware of nagging, which she characterized as repeating the same thing over and over in the same way.

“Try a different avenue, try a different tone, try a different time of day,” Ms. Jackson urged, like perhaps writing an email rather than squabbling about messes at the end of a long workweek.

Be deliberate about voicing your expectations, Ms. Jackson said, and revisit them often, because regular check-ins can prevent resentment from building. She declined to offer a specific time frame for those conversations, as it varies from household to household, but she encouraged anyone moving into a new season in life (after a new baby or a job change, for instance) to talk about household expectations.

“Even if there’s just been a shift in preferences,” she said, “that needs to be vocalized.”