Decide what you want to part with, and find out which things relatives will take. She likes to use a sticker method, placing different colors on pieces that will be donated or sold. If the process is truly overwhelming, it can be worthwhile to bring in an organizer, decorator or appraiser who’s willing to be paid by the hour to assist.

If you suspect you might have something valuable, contact one of the top auction houses. “You shouldn’t be intimidated by the brand and the name,” Mr. Harrington said. If they’re not interested, they will refer you to other sources. If they are, they will ask for photographs and any paperwork you may have, to get a sense of the value of a piece. So will estate buyers, though Mr. Balaish said that wider shots of the home were more useful, because what you might consider most valuable might not actually be.

One recent client wanted to sell two 19th-century chairs that had originally cost her $12,000. “The current market for them is $1,000,” Mr. Balaish said. “But she had these plastic lamps that she bought for almost nothing. They’re midcentury — we can pay her more for that.”

Adam Blackman, co-owner of the Los Angeles furniture gallery Blackman Cruz, which deals in new and old furniture, points out that there are many regional and local auction houses that sell furnishings — and that sellers needn’t be discouraged if their belongings are rejected. “Go down the list,” he said. For 20th-century pieces he would contact Wright auctions in Chicago. Bonhams, which has offices in a number of U.S. cities, takes finer items. Abell Auction Company in Los Angeles is a good final stop, he said, with weekly auctions.

It helps to keep in mind what kinds of pieces are easier to sell. Smaller, more versatile items like side tables and compact desks are more likely to find a home, Ms. Baker said. Mr. Harrington said that the supply of antique dining tables far outstripped the demand, but that flip-up or expandable versions had some appeal — unlike big roll-top desks and slant-front cabinets.

“People don’t read or write the way they used to,” he said.