Peek inside any one of design firm Ideo's conference rooms, which speckle the globe from Silicon Valley to Shanghai, and you will see what looks like the Ten Commandments of brainstorming etched onto the walls.

"Defer judgment!" reads one stencil, admonishing the room's occupants to think twice before shooting down a seemingly wild idea.   

"Be visual!" screams another one, amid ample whiteboard space and oversized sketchpads, which have spawned prototypes for some of the most innovative products of the decade, including the Apple mouse and the Palm V.

Brainstorming is so ingrained in Ideo's culture that "we actually put these rules on our business cards and give them to everyone," says Brendan Boyle, a partner at the firm who also teaches creativity and design classes at Stanford University. "It's almost like we evangelize brainstorming."

Each day, Ideo's staffers spit out hundreds of ideas, and probably burn through just as many PowerBars. Here's how they spark good ideas during brief sessions in the office, and how your company can, too: 

Running a Brainstorming Session: A Meeting of Different Minds  

Boyle recommends inviting a mix of senior and junior staffers from a range of disciplines—from finance to design to engineering—that would suit the end goal of the session. In other words, he says, "make sure you get the chemistry right."

Keith Sawyer, a professor of psychology and education at Washington University in St. Louis, calls it "group genius," or the idea that innovation requires cross-pollination from seemingly unrelated fields.  But in his book of the same name, he stresses that the people in the group must have enough in common to share the same vision. 

"There needs to be that feeling of, 'we're in this together, we're doing something that's really important, and we really need to pull together and get this done,'" he says. "Without that sense of ambition, diversity can actually be a challenge and make the team less effective."

Running a Brainstorming Session: Set up the Space  

"The worst way to do brainstorming is to just sit around and talk," says Sawyer, who recommends holding the session in a bright, spacious room that allows for standing up and walking around.

Make sure there are plenty of ways for people to externalize their ideas. Provide materials that people can manipulate, he adds, such as markers, bulletin boards, or even modeling clay.

Ideo uses easel-sized Post-it Notes to sketch out ideas as they flow. The method has led to many successful products, including that for the Jumperoo by Fisher-Price, which is similar to a doorway jumper for infants and toddlers but has a freestanding base.

"Moms hated the jumper that hung from doorways because it blocked key passageways and they were scared it would fall down," says Boyle, who called a brainstorming session to solve the problem. "One thing we love to do is quick sketches, and out of that session was a quick sketch of the prototype that we made for the Jumperoo."

The product, now five years old, sells about 1 million units a year and has become something of a YouTube sensation. With more than 6,000 videos of babies bouncing around in Jumperoos on YouTube, Boyle says, "people love that product—it was a tremendous success."

Running a Brainstorming Session: Check Your Title at the Door

Nothing kills a brainstorming session—or encourages brownnosing—like an intimidating authority figure, says Boyle, who recalled a meeting at his first job out of college, during which the boss came in and hijacked the brainstorming process. "Of course everyone sat back and agreed with him," he says.  

That doesn't mean the boss shouldn't attend, adds Boyle. He or she just shouldn't sit at the head of the table and assume control.

That said, it's usually a good idea for someone to assume the role of facilitator, he advises, whether that means just standing in front of a whiteboard and jotting down ideas, or keeping staffers from dwelling on one idea for too long.

Dig Deeper: Unleashing Employee Creativity

Running a Brainstorming Session: It's all About the Quantity

The goal of the brainstorming session should be to generate as many ideas as possible. Boyle notes that many brainstorming newbies make the mistake of trying to come up with the best idea, which encourages too much judgment.   

"You certainly don't want ideas being judged negatively, like, ‘Oh, that idea's terrible. We've tried it before,'" he says, since it can kill confidence and keep people from voicing less conventional ideas.

At Ideo, about 75 to 100 ideas are generated per brainstorming session. Have the facilitator keep the momentum going by pushing for more ideas, similar to the way an auctioneer would push for a higher bid. "Tell them, ‘All right we just got to 50, let's get to 60, let's get to 75,'" says Boyle. "Once you reach your goal number, then you can go back and be ruthless and evaluate everything. Because you have more ideas, chances are that you'll probably arrive at a better idea."

Dig Deeper: The 48-Hour Rule

Running a Brainstorming Session: Make Generating Ideas a Part of the Culture

"A brainstorming session is almost like a band-aid—a quick fix," says Sawyer. "It's not necessarily going to happen on Friday at 2 p.m., when we've got the brainstorming meeting scheduled."

The best way to brainstorm, he says, is to infuse the process into your company's culture. In his book, he lauds the Delaware-based firm W.L. Gore & Associates, which makes waterproof fabric. Calling it "dabble time," the company asks its staffers to spend 10 percent of their week working on whatever they want.

"All of their new innovations emerge during this dabble time," adds Sawyer. "The idea is that new products emerge from the bottom up. They don't come from an R&D lab and they don't come from marketing surveys. They come from individual employees independently deciding how to pursue their time."