After years of growing their ventures, many small-business owners end up like Eric Poses — calling all the shots and rarely getting a moment's rest.

"I do everything," says Mr. Poses, president of All Things Equal Inc., a Miami board-game company he founded in 1996 that today earns about $2 million in annual sales. "I'm still making all the decisions, which takes up a lot of my time."

Jamie Damato Migdal, owner of AnimalSense Canine Training and Behavior Inc. in Chicago., says an employee might make a good deputy is if he or she acts in the company's best interest without prompting.

For owners who've built their businesses from the ground up, letting go some control to a second-in-command can be nerve-racking. But experts warn that there are potentially worse consequences to maintaining a tight grip on an enterprise, including burnout and problems stemming from unexpected emergencies, such as if an owner suddenly falls ill.

Sandy Hansen, owner of AgVenture Feed & Seed Inc. in Watkins, Minn., understands those dangers all too well. She was thrust into entrepreneurship in 2003 when her husband, the feed-supply company's original owner, died of leukemia. He had never appointed a top deputy in the nearly 20 years he ran the business, nor did he create a succession plan.

"He didn't get around to it," says Ms. Hansen. "We were in near bankruptcy for three years trying to learn information only he knew." The business has since rebounded, she adds.

Some owners avoid recruiting a No. 2 because they have difficulty trusting someone to become close to their business, says Daniel M. Murphy, co-founder of The Growth Coach, a business-coaching franchise system based in Cincinnati.

But oftentimes owners reach a point where they realize they just can't keep at it alone.

"Invariably an owner will hit a wall where they feel overworked and like a prisoner to their business," says Mr. Murphy. "They need to let go."

In general, a No. 2 is responsible for overseeing day-to-day operations, such as employee schedules, customer or client issues and other basics, he says. With these responsibilities out of the way, business owners can focus on the big picture: growing their enterprises, says Mr. Murphy.

"The chief executive is the person with the vision who makes sure there is a plan in place to get there," he says. "Their job is to create jobs for other people. They're leaders, not doers."

A business owner's sidekick should ideally have skills and a working style that are complementary to what the business owner possesses, says Robert M. Donnelly, professor of entrepreneurship at St. Peter's College in Jersey City, N.J. "Don't expect the person to be as good as you at what you do," he says. "You're really hiring a No. 2 to be good at the things you're not."

Joanna Horobin, chief executive of Syndax Pharmaceuticals Inc. in Waltham, Mass., says she has a second-in-command who works at a calculated, detailed pace, whereas she tends to keep up a steady, swift momentum. "Without somebody like Bob, I run the risk of my big ideas missing people and not getting translated," she says of her No. 2. "I have more of a relentless leadership style."

Now is an ideal time to hire a top lieutenant due to the high number of professionals who are unemployed, says Mr. Murphy. "There's such great talent out there that's affordable," he says.

Just make sure to do your due diligence in choosing this person by checking references and preferably investing in a background investigation of him or her, adds Mr. Murphy. "This is a critical hire," he says, given the high level of responsibility and trust required of a top lieutenant.

Business owners may also want to consider grooming an insider for the right-hand position. For Kate Koziol, owner of Chicago-based K Squared Communications Inc., the right candidate became apparent a few years ago when a new client flew into a panic while she was vacationing and couldn't be reached.

A mid-level staffer at the public-relations firm stepped in and quickly resolved the matter. "It was a true test because it just happened and she made the best of it," says Ms. Koziol, adding that she's been prepping the employee for the No. 2 job ever since.

Another sign that an employee might make a good deputy is if he or she is always acting in the company's best interest without any prompting, says Jamie Damato Migdal, owner of AnimalSense Canine Training and Behavior Inc. in Chicago. She says she recently appointed a staffer who regularly demonstrates this kind of behavior as her second-in-command.

"She really shows great initiative and an understanding of what happens around here," says Ms. Damato Migdal of her chief aide. "She's looking out for me, the staff and the bottom line."

Sarah E. Needleman has been a reporter for Dow Jones since 2001 covering job hunting, executive recruitment and other career-related topics. She writes Small-Business Boss, a weekly column about the challenges that first-time entrepreneurs face in managing employees.