Accessories can turn a house into a home.

Accessories can turn a house into a home. Credit: Newsday/J. Conrad Williams Jr.

Accessories are, by definition, needless things that make life a little sweeter. Like Champagne or movie stars, their nonessential natures leave only one possible justification for keeping them around: We adore them.

That's particularly true in today's streamlined interiors. The home accessory is no longer an afterthought: Only the most deserving objects should earn a spot in your space. "It's a new look, with less things and stronger elements," says Glen Cove interior designer Greg Lanza. "It's very curated, very selective and super clean."

To get the latest look, you'll have to make a frank assessment of your things. No matter if your home is trendy or traditional, careless assortments of knickknacks have become a no-no. Edit your collection down to only your most cherished, useful or gorgeous objects -- or clear it all out and buy a few choice additions.

Next, sort your selections into small groupings that will punctuate the space -- not clutter it, Lanza says. "Clean surfaces are important now. People have busy lifestyles, and they want that easy look."

Finally, it's time to open your mind and look for ways to make static items more dynamic. Push the boundaries with surprising and clever juxtapositions, such as combining old with new, putting things in unexpected places or finding new uses for ordinary objects.

Whether you're using accessories to give the room an eye-catching focal point, a seasonal update or that intangible sense of harmony, you should be able to describe the resulting impression with a single word: deliberate. Here's how designers make it happen.

COLORFUL CHARACTER

For Huntington designer Eileen Kathryn Boyd, an interior is not unlike any other composition, such as a painting or photograph -- and the same design principles apply. "You're looking for proportions -- small, medium and large . . . You want a foreground, a middle ground and a background, so you have these layers." Accessories are the final brush strokes that complete the picture. "When we place the accessories, it finishes the story. It defines the room and gives the room personality," Boyd says. "I think a room looks pulled together if all the accessories have the same color story." In her family room in Huntington, hot pink accents top off the chocolate brown. "Accessories give a room a real surge of energy and come-alive feeling," she says.

ANYTHING BUT ELEMENTARY

These eggshells and snail shells previously inhabited a perfectly logical spot in designer Greg Lanza's Glen Cove home -- his paneled library. "On the shelf, it was Sherlock Holmes-y," Lanza says. To change things up, he took them out of context, elevating them -- both metaphorically and physically -- from charming curiosities to objets d'art. Displaying traditional shelf accessories on the wall gave them a modern twist while livening up their new home: the living room. "I wanted to tone down the formality in the living room and make it an easy entertaining space," he says. "I made it into this Italian-Anglo-modern look." An Italian coffee table, a signed modern rug and the accessories-turned-wall-art "made this beautiful composition from different periods -- from the '60s to 2011," he says.

RIGHT AT HOME

Objects should look like they belong there, says designer Mercedes Courland. "I prefer that the accessories relate to the function of the room," she says. For instance, in this bar at her Roslyn Harbor home, glass bowls, fruit, Champagne and glasses serve up some style. "I like to tie in the colors of the interior so it all blends in a more monochromatic feeling, which makes things look like they belong and can make the space appear larger," she says. "On the other extreme, I use accessories to 'pop' in a space that needs vitality or energy. It all depends on the feeling one wants to create in the room." This walkout lower-level room opens onto a yard full of yellow flowers and a pool accented with green and yellow glass mosaic, so Courland used a lemon and lime theme to bring that sunny outdoors in.

A LITTLE OF THIS

This artful mix of trendy new pieces and flea market finds was part of the 2011 Hampton Designer Showhouse design by Suysel dePedro Cunningham and Anne Maxwell Foster of Manhattan-based decorating firm Tilton Fenwick. The curves and points and coppery finish of the pagoda lanterns from HomeGoods provide a lively counterpoint to the sleek and ultra-current Lucite tray from West Elm, while the vase and green dish -- both flea market finds -- bring character. "The arrangement has a nice symmetrical balance . . . with asymmetrical interest between the books and the vintage green tray," Maxwell Foster says. "The flowers are purple hydrangeas. We chose them for the visual contrast against the green velvet sofas as well as being a local, in-season flower in the Hamptons." They would know -- both designers rented a summer place in East Hampton.

Accessorize like a pro

Are you an accessories amateur? Try these tips for topping off your interior like a pro:

Picture it

Photograph the room to figure out where you've got too many accessories -- or not enough, says Huntington designer Eileen Kathryn Boyd. It will be easy to spot holes in the design. "It's glaring, what's missing. The camera shows all the imperfections."

Go a little mad

Thanks to AMC's cable TV show "Mad Men," midcentury modern accessories have gone from ironic to iconic. For instant retro panache, shop retailers for vintage-inspired pieces or comb flea markets and antiques shops for the real thing.

Layer it on

Layering different styles gives depth to your display. Try layering old items with new ones or pricey pieces with frugal finds, suggests Manhattan designer Anne Maxwell Foster, who rents in East Hampton for the summer.

Odds are good

Designers agree, odd-numbered groupings are the most visually pleasing -- especially groups of three. "Two is flat -- three gives it dimension," says Scarsdale designer Jolie Korek, who owns a home in East Hampton.

Make something clear

Translucent elements, such as Lucite or glass, will bring some geometric interest and add a little shine to your design. A clear glass vase has great versatility: Fill it with flowers in the summer, candles in the winter -- even sports tickets during football season, as Roslyn Harbor designer Mercedes Courland does.