When Regan Billingsley was a child, her mother let her design her own bedroom — with just a few conditions.

“She told me, ‘You can do what you want, as long as it’s from a Laura Ashley book,’ and if I was willing to do all the work,” Billingsley said.

The room ended up with dark blue walls covered with photos, posters and artwork, Billingsley said. It was a true reflection of her style and creativity.

Now 37, Billingsley has channeled that creativity into an interior design career. Billingsley has worked for more than 12 years in Los Angeles, New York City and Maryland on both residential and commercial spaces. She will also be the guest judge in this year’s Kid’s Room Contest.

One of her latest projects was a room in the 2013 DC Design House. Billingsley designed a teenage boy’s bedroom with urban decor and a mix of vintage and contemporary pieces.

“I draw from my own experience when designing a room,” Billingsley said. “How lucky was I that I had parents who let me express my creativity in my room? I think about that when I’m designing rooms for other kids.”

We chatted with her about her style choices, her advice for designing a kid’s room, and what she is looking for in a winning space. Here is an edited transcript.

What are your tips or tricks for decorating a kid’s room?

Try to make it a space of their own. No matter what age they are, kids have an idea about what they want in their room. In the same way that parents want a master bedroom that is a retreat or relaxing, kids have an idea about what they want their space to look like. I try to work with their favorite colors and the activities they do. One thing I consistently try to provide is a nook area, whether it’s converting a closet or having a canopy bed. It’s their own little space they feel comfortable in. They feel cocooned. I’ve re-created that consistently.

Another thing is color. Kids like pink and blue. A lot of times I work with those colors. But parents want something that will grow with them. We will mix a more sophisticated color, such as a shade of purple, so it’s not a pink overload. I worked on a child’s room recently with a boy whose favorite color is bright orange. His parent’s eyes bulged out when he told me. We did an accent wall behind the bed and kept the rest of the room neutral. It’s a happy medium.

Are you seeing any new trends for kid’s room design?

Everyone says to me, “I want a room that kids can grow into.” They are investing in the furniture. There is a lot of furniture now that can be converted into something else as the child grows. A dresser in a nursery can be used as a changing table. If you’re investing in good, quality furniture, it should last. Start with a good foundation and add accessories for their age and interests.

There are always furniture trends, but I don’t really design with the trends. A kid’s room is all about personality. Trends are not always reflective of who your clients are.

I like to ask what a child is most interested in and build on that. I had a child who loved music, so I worked with the parents to build around a red guitar as his room’s theme. Another 4-year-old girl loved showing off all her jewelry. We got her a vanity with little jewelry boxes. Those are accessories that she may lose interest in, but the vanity will last. I think it is important in kids’ rooms that they feel it is a space of their own and inspires them.

How do you approach teenagers’ bedrooms, including the room you created for the DC Design House?

When kids get older, they come into their own. Teens collect stuff. That was one of the ways I brought personality into the DC Design House. Every teen is collecting stuff — things they are interested in. Take those collections and turn them into something significant. You can put them into a shadow box or frame, and you can turn them into art. Put collections up on a shelf. For things less display-worthy, it’s important to have baskets and bins and boxes — places for them to throw stuff into, instead of drawers. It gets clutter out of the way.

What are you looking for as a judge for the Kid’s Room Contest?

I think there are so many creative parents out there, and do-it-yourselfers. What I am looking for is functionality and originality and personality. I think it’s important to have a space that parents are happy with, but also reflects their kids. And a functional space. It shouldn’t look like they just took the junk out for the picture.