When Sarah Meyer and her boyfriend, Ricardo Vieira, decided this spring that they wanted to buy a condo in Northern Virginia, they didn't expect that finding a real estate agent would be difficult.

But after spending three weekends interviewing five potential agents who came highly recommended by friends, the couple, first-time home buyers, realized the process would be no cakewalk. They finally chose one, but he sent them e-mails of single-family homes for sale instead of condominiums. He found them properties far from their desired location along Metro's Orange Line. And he did not allocate sufficient time for them.

"We did not connect," Meyer recalled, adding, "He probably had bigger fish to fry."

Eventually, they found another agent and bought a condo in West Falls Church.

With about 3 million licensed real estate agents in the United States, according to the Association of Real Estate License Law Officials, finding the one who will best suit your buying or selling needs can be confusing and challenging.

Further complicating the decision is the barrage of direct mail -- often featuring professional sports team schedules, school calendars or refrigerator magnets -- that many agents send regularly to residents in targeted neighborhoods to solicit business.

As a result, buyers and sellers frequently select agents in a haphazard way, experts say. Out of kindness or convenience, they may hire their friend, neighbor, colleague's spouse, or the agent who sends the most fliers, without knowing much about the person's qualifications.

The most common mistake is hiring an agent too quickly, "before knowing enough about his or her honesty and integrity, and about whether he or she will perform as you want them to," said Gary W. Eldred, author of "The 106 Common Mistakes Homebuyers Make (& How to Avoid Them)" (John Wiley & Sons, 2001).

Consider Rachel Posell and Steve Greenstein, a Silver Spring couple who in 2002 wanted to buy a home in Takoma Park. They picked their real estate agent on the recommendation of Posell's best friend. But they never investigated his credentials. He failed to show them any houses in Maryland, they later learned, because he was not licensed there. In the end, they gave up on buying a house and rented in Silver Spring for a year.

To find the best agent to suit your buying or selling needs, begin by taking the hiring process seriously, said Shelley O'Hara, co-author of "The Complete Idiot's Guide to Buying and Selling a Home" (Alpha Books, 2003). "The decision is important because you'll be with that person and they can advise you on selling or buying prices, on financing, and on negotiating with the buyer or seller," she said.

Then ask yourself what you would like your agent to do for you, suggested Eldred. Do you want that person to familiarize you with various neighborhoods, or just to alert you when homes come on the market? Do you want someone who will advise you on how to prepare your house for sale or will you do that preparation yourself? Do you need someone to help you find an inspector, an appraiser and a mortgage company, or mostly to write up your contract and help you make your bid?

Once you know the answers to those questions, seek recommendations from friends, family, co-workers, members of neighborhood associations or religious organizations, advised O'Hara. But before following up on any names, ask people what they liked and disliked about the people they mention.

Another information source for possible agents is the Internet. For example, members of online community discussion groups can ask one another about the pros and cons of specific local agents. Some Web sites such as www.reals.com feature directories of agents across the country.

Of course, it's possible to randomly meet agents who turn out to be helpful. That happened to D.C. resident Beth Hanak and her husband, Dan Orcutt, who met their Long & Foster Real Estate agent at a condo open house in 1999. Hanak was impressed that the woman talked to each person in the room. Though the couple didn't buy that property, they contacted the agent afterward and met with her to discuss their housing desires, budget and financing issues. The agent found a condo in Van Ness that appealed to Hanak and Orcutt, and she instructed them to put in an aggressive bid against three others. She "got it for us," Hanak said.

For their part, agents often rely on open houses more as a way to meet potential customers than as a way to sell a particular home.

Once you identify a few potential agents, meet and interview them in person to assess their qualifications and to see how well you connect before hiring them, authorities stress. Ask for references, and check them.

Find out each potential agent's specific plan for getting your home seen by prospective buyers, recommended Rodney Rice, co-founder and co-chief executive of ServiceMagic, a Colorado-based online company that connects homeowners to service professionals.

Buyers and sellers should ask candidates what types of properties they specialize in, suggested O'Hara. She explained that if the agent's strength is high-end homes on the west side of town and you're looking for moderate-priced homes on the east side, the match might be a poor one.

Additionally, ask the agents about their education and experience and whether they work part time or full time, O'Hara said. But she cautioned that intangible factors matter, too, and that a new agent who "has a lot of drive" or a part-time agent who seems very accessible may be the best choice.

Do some background checking on agents you are considering hiring, said Dorcas Helfant, past president of the Chicago-based National Association of Realtors and principal broker at Coldwell Banker Professional in Virginia Beach. She recommends calling your state licensing agency to find out whether any complaints have been filed against a particular agent. Also, you can check the status of agents who belong to the National Association of Realtors with the local Realtor organization and learn whether they are in good standing, meaning they have adhered to the organization's code of ethics and standards of conduct, she said.

Once you narrow down your pool of candidates to a qualified few, the choice is more personality-based than scientific, said Helfant. Posell and Greenstein found that to be true after their initial bad experience with the agent who wasn't licensed in Maryland. When they started another housing search in 2003, they met with an agent who came highly recommended and knew the Silver Spring neighborhoods where they wanted to buy.

But even better, said Posell, she was "matter of fact and no nonsense. . . . Her approach worked for us."