Clutter. We all have it, and we all fight it—some of us more successfully than others. That's why a cottage industry has grown up around it: The National Association of Professional Organizers has 4,000 members and growing, and the Container Store is a nearly $650-million-dollar-a-year business.

"Nothing looks worse than clutter, and clutter happens because there's no place for something," says architect John Coplen of Baltimore's Alter Urban Design Collaborative.

But finding that place can be daunting, especially in areas of the house most likely to attract mess—out-of-the-way spaces where it's easy to toss things when you're clearing out the more trafficked rooms.

We surveyed designers and homeowners who got it right in these trouble spots, from bedroom closets and kids' rooms to the mudroom and pantry. From everyone we spoke to, clear themes emerged that can be applied universally.

Review and edit. "If you understand what you have, it can really help," Coplen says. In other words, pull everything out and put back only what you really need and use.

Be flexible. Storage spaces should be designed to evolve with your needs. That means adjustable shelves and bins that might hold action figures for a toddler but that can also accommodate sweaters or schoolbooks for a teenager. "I always try to find something that has a dual purpose," Alexandria homeowner Lynn Tanger says.

Organize around existing habits. Don't create some fancy system that your family won't intuitively use. For example, says architect Ankie Barnes of Barnes Vanze Architects in DC, "kids are taught in school to use a cubby as a repository for mess and as storage," so reinforce that habit with cubbies at home.

Make it pretty. Paint the inside of a closet a vivid color, or put a jaunty cushion on a bench in the mudroom. "It's psychological," Arlington designer Nicole Lanteri says. "You're more interested in making that space look neat."

Read on to learn how these and other experts tackled a particular problem space.