When preparing for a job interview* most of the effort goes into anticipating the questions that will be asked by the interviewer and preparing smart and persuasive answers. What is often neglected, however, is the importance of the questions that the interviewee should ask. The right questions will not only serve to impress the interviewer, but will also enlighten the job seeker as to how good a fit the job might be for him / her. Here are six particularly good ones:
1) "Once I'm oriented to the basic responsibilities and people I will be working with, what will be the top two or three priorities for me, and how will my success in achieving them be measured?"
Most job descriptions list a wide variety of responsibilities for the prospective employee. This question seeks to narrow the list and identify what management will be most closely looking at in their new employee's performance. You need to pay close attention to the answer to this question, as it will cut through the generalizations and clutter contained in most job descriptions. As for the measurements of success, they should ideally be as concrete and quantifiable as possible, rather than resting on the boss' subjective evaluation.
2) "Relatedly, over the next year what ONE accomplishment would you be most impressed with?"
You should really understand the organization's primary need as it relates to your performance. If your interviewer hesitates to pick one accomplishment, try phrasing the question in historical terms: "In years past, what kinds of accomplishments of people who've held this position have been most significant?"
3) "What are the most significant challenges I am likely to encounter in this position?"
The goal here is to try to uncover issues related to working relationships and / or organizational culture resources. Pay very close attention to the way these questions are answered. It is unlikely that you are going to be told straight out that you will be working for a very difficult boss, or that Management doesn't fully buy into the mission which the open position supports, or that there's a "good old boy" culture that makes it tough for women to fit in, but tone-of-voice and body language can indicate whether the interviewer is feeling uncomfortable about answering this question. You should always seek coroboration from multiple sources if you have concerns about the challenges you will face.
4) "What are the qualities that the most successful people in this position / organization possess?"
Here you are looking for more specificity than is generally indicated by such terms as "excellent interpersonal skills," "exceptional organizational abilities," "ability to multi-task," etc. Try to find out what about the position or organization makes these qualities the ones that are especially valuable. For example, with proper questionning you might learn that "excellent interpersonal skills" are required because of something like historical rivalry between departments, or a troubled client relationship.
5) "How has this job evolved over the past few years? How do you see it evolving?"
I just like this question - I think it demonstrates to the interviewer that you are thinking beyond simply landing the job, and focusing as well on your longer-term prospects.
6) "Is there anything I've said, or that I haven't said, in our talk today that leaves you with any significant doubts about my ability to succeed in this position / at this organization?" (Obviously this is a question to be asked at the end of the interview).
This question has three aspects to recommend it. First, it expresses an interest in landing the job from a different stance than more standard passion-related or qualifications-related statements might (e.g. "I would really love to work for your organization" or "I know I have what it takes to succeed here."), so is a potentially valuable supplement to those. Second, it demonstrates that you are open to hearing critical feedback. And third, it gives you an opportunity to address lingering doubts that the interviewer might have, but which might not be revealed if this question were not asked.
* These questions are also important to ask in an "informational" interview (I actually prefer to use the term "exploratory interview"). Remember that this kind of interview offers an opportunity for you to impress the person you're talking to, which may lead to enhancing your prospects at some future point down the road when an opportunity might arise.