FIND THAT ONE thing that can serve as the inspiration for the color palette,” said Caitlin Murray, founder of Los Angeles’s Black Lacquer Design, when asked how to tackle a room’s décor. “It’s such an easy cheat.” In the case of a blandly modernized room in West Hollywood, the interior designer used an abstract painting as her jumping-off point. Guided by its mix of neutrals and pastels, she set about giving the bedroom enough character “for a lovely, spirited lady of a client” without over-energizing a space meant to be serene.

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Ms. Murray gave the artwork’s soft pinks and blues their boldest expression in the blush velvet-upholstered bed and the blocky dresser, from CFC furniture, whose color, though technically Slate, reads dusty indigo.

Elsewhere, Ms. Murray deployed pattern in interesting ways. Pronouncing all-white ceilings and walls “so ‘Trading Spaces’ circa early 2000s,” she papered a single wall in inky cheetah speckles. A rug’s crazy quilt of browns is enlivened by a ribbed texture.

“A lot of stuff can work as long as you stay within parameters,” said Ms. Murray of her focused formula. “I don’t like to introduce a color that isn’t found anywhere else, because it becomes an eyesore.” This dictum also applies to black. In this room, she used both the lamps and the throw to introduce bits of punctuating ebony. “You can’t have [black] in a vacuum,” she said.

The result? A careful marriage of vivacity and quietude that may well lull one to sleep—but not out of boredom.

1. Grab a Guide

Ms. Murray first defined her color boundaries with an artwork. “You can just stay within those realms, and it will feel cohesive,” she said. For an equally inspiring launchpad, look to “What We Were Thinking” by Craig Greene, Mixed-Media, Canvas, Unframed, $950, chairish.com.

2. Dress it Down

A clever array of angles distinguishes a shapely Art Deco mirror, a nod to the home’s 1920s roots. The mirror’s finish, a coat of gray wax on blond reclaimed Douglas fir, softens the edgy frame. Large CFC Ludwik Floor Mirror, $3,263, meadowblu.com.

3. Get Tough

The voluptuous bed “needs something to make it feel a little bit more tailored,” said the designer. Abut a structured perch, like the almost-industrial Fabulous Big Bench, $791, chairish.com.

4. Limit Your Quiver

Echo elements for continuity. Ms. Murray chose a loosely corresponding mate for the amethyst vase on the dresser to sit bedside. Start your pair with this organic Pia Wüstenberg Sculpted Blown Glass Vase, $374, 1stdibs.com.

5. Play with Shape

In neutral colors, even structurally commanding pieces, like the stumpy plaster bedside table, work. This handmade sculptural nightstand is equally quiet: Phyllis Waterfall Plaster Accent Table, $675, okenhouse.com.

6. Don’t Be Afraid of the Dark

Black accents, like those of the bedside lamps, ground elements that might otherwise contribute to chaos. For your own ballast, try a pair of Waylande Gregory Black and White Lava Large Chubby Lamp, $1,850 each, 1stdibs.com.

Photo: F. Martin Ramin/The Wall Street Journal

7. Go Big with Pink

“The fabric on this bed is just so scrumptious,” said Ms. Murray. Make your own luscious statement in similarly luxe Kravet Madison Velvet Rosewood Fabric, $42 per yard, decoratorsbest.com.

8. Hew to Your Hues

A wool rug lends a patchwork of the desert tones found in the painting—the large-scale pattern playing well with the dappled wallpaper. Try this comparably chunky option: Bran Rug in Saffron, Khaki, Cream, from $1,199, burkedecor.com.

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