You don’t need a degree in interior design to recognize something is terribly wrong.

The museum-quality painting looks like it’s floating too far above the chest of drawers.

The trio of lithographs over the sofa are beautifully framed but get lost because they’re too small. And what is supposed to be a gallery wall looks more like jumble in a junk store.

We may know what we like in art, but we often don’t know what to do with it. Astrid Newton Rush, a Weston, Fla., interior designer and member of the American Society of Interior Designers, let us in on the “Trade Secrets” of picture hanging to avoid the hang-ups of improper display.

Sofa signals

One painting over a sofa, even if it’s large, tends to get lost on a large wall. The art should cover about 75 percent of the width of the furniture below. If it covers less, add embellishment – other art, sconces, candelabra or decorative wall shelves.

Another common mistake is using two small pieces of art over a sofa. One solution is buy a big picture for the center and hang the smaller pieces on either side. Or you could add a larger piece to the left of center and stack two or three pieces of art vertically on one side and a sconce on the other.

Once you have the art, measure the space you think you will need. Using those dimensions, lay out the art on the floor until you find the combination that works. Remember, any group of pictures should be thought of as a unit. Vertically related pieces should be hung 1 1/2 to 2 inches apart. For a compact composition, space art 2 to 3 inches apart horizontally or 4 to 6 inches apart for a more spread-out look.

Don’t hang the art too high. It should be anchored to the furniture below – the bottom of the frames should be no more than 8 to 10 inches above the sofa.

Family style

We all have more family photos than we can ever display. The trick is selecting those that tell a story and look best together. Rush suggests starting with an inspiration piece. Her inspiration came from a sepia-tone photo of her husband’s parents she had professionally framed in a brown-and-black frame. She unified the rest of the arrangement with the same cream-colored mats. The black-and-white photos were put in black frames and the sepia photos in brown frames. You should keep black-and-white photos separate from color photos for more drama. Frames of varied shapes and sizes create a more interesting composition.

To figure out the arrangement, use a large piece of paper and tape it to a tile floor. When you find the arrangement you prefer, trace around the frames. Finally, tape the paper to the wall and poke a hole through in each spot where the frame should be hung.

Theme song

A good way to unify a wall arrangement is to select a theme.

Rush’s client Terri Gonzalez loves botanical prints and thought that they would make the perfect arrangement over her Martha Stewart sofa. She bought a botanical calendar for $12.95 and, with the help of Rush, selected six florals to be professionally framed with black fillets and black frames.

“The grouping reads like a large piece of art,” Rush said.