1. Answer your cell phone. If you forget to turn it off and it rings, turn it off immediately, apologize profusely and look mortified.
2. Ask questions about the company that could have easily been answered with a modicum of research. I've had candidates say, "So what exactly do you guys do?"
3. Badmouth an old boss. I'll assume that'll be me you're talking about some day.
4. Pretend you have no weaknesses. Or tell me that your biggest weakness is perfectionism and you work too hard. You might as well wear a sign saying: "I'm BS'ing you." Candidates who can't or won't come up with a realistic assessment of areas where they could improve make me think they're lacking in insight and self-awareness or, at a minimum, just making it impossible to have a real discussion of their potential fitness for the job.
5. Share too much personal info. I once had a candidate tell me way too much about the sex column she wrote for her campus newspaper. If I had been talking to her at a party, I would have been fascinated, but it was inappropriate for a job interview.
6. Lie. It doesn't matter how great the rest of your interview is, if you and lie and it's discovered, you're no longer a candidate.
7. Ramble on endlessly. Rambling raises doubts about your ability to organize your thoughts and convey needed information quickly and signals that you're not good at picking up on conversational cues about where your interviewer wants to take the conversation. Instead, give direct, concise (two minutes at the most) answers. You can always ask: "Does that give you what you're looking for, or would you like me to go more in depth about this?"
8. Be as quiet as possible. It shouldn't be like pulling teeth for me to get information out of you. If you're shy, I empathize, but you've got to help me get a sense of who you are.
9. Don't ask any questions. I want to know that you're interested in the details of the job, the department you'll be working in, your prospective supervisor's management style, and the culture of the organization. Otherwise, you're signaling that you're either not that interested or just haven't thought very much about it.
Alison Green is chief of staff for a medium-size nonprofit where she oversees day-to-day management of the staff as well as hiring, firing, and staff development. She is working with the Management Center to coauthor a book on nonprofit management. Her writings have been published in the Washington Post, the New York Times, Maxim, and dozens of other newspapers. She blogs at Ask a Manager.