FORTUNE -- When David Bakke was looking to move from restaurant management into finance, he immediately thought to contact a friend who worked at a mortgage-lending firm in Tampa. Based on the friend's recommendation, Bakke was hired for a financial analyst position at the company.

Then things turned sour. The job turned out to be little more than a secretary position. Instead of learning about risk management and financial forecasting as Bakke's friend had promised, he was making photocopies, answering phones, and taking notes in meetings. When his friend learned of Bakke's dissatisfaction, he tried to guilt trip him, saying, "If you quit, that's going to damage my reputation around here. I got you hired on the spot." Shortly thereafter, Bakke gave notice and left the firm. His friend hasn't spoken with him since. "Fortunately, with my restaurant management background, I was able to get back into the industry," says Bakke, 45, who now is working in financial services in Atlanta. "It wasn't like I suffered any financial hardships out of the situation, but I did lose the friendship, which is unfortunate."

As our personal and work lives lap into each other, it heightens the need for better communication and forethought to avoid an uncomfortable situation like Bakke's. The stakes are higher, because you don't want to lose your friendship -- or your job. Since we're more likely to drop our guard or assume our friend has the same perspective we do, it's important to bring hidden assumptions into the open. Give as much thought to due diligence and professional etiquette with your friend as you would with any work contact.

Career strategist Darrell W. Gurney calls it a "free trade networking agreement," in which you explicitly discuss the terms of an introduction, recommendation or other situation. You might say, "I'll make the introduction. I'll leave it to you to nurture and make the most of that connection," says Gurney, author of Never Apply for a Job Again: Break the Rules, Cut the Line, Beat the Rest. Or, in Bakke's case, his friend could have said, "I'll recommend you for the job. You need to determine that it's the right fit, or it could hurt my reputation."

By Katherine Reynolds Lewis, contributor