When you're preparing, these are the six most important things to make sure you know:
1. What is the job all about? It might sound obvious, but plenty of people interview for jobs without really understanding what they'd do all day. If you walk into an interview not fully clear on the details of the job you're applying for, you risk looking as if you don't take your career or the interviewer's time seriously.
2. What will it take to do it well? If you don't understand what it will take to excel at the job, you won't be able to show your interviewer why you're a strong candidate. That means you need to prepare by thinking deeply ahead of time about what skills, talents, and traits will make the difference between doing an OK job in the position and doing a great job there. One good exercise is to imagine that you're a co-worker of the person in the position for which you're applying. What would you expect from them if they excelled at the work? Another exercise: If you were hiring for this position, what would you look for in candidates? What sorts of things would concern you?
3. Why do you think you'll do the job well? This is different from the last question; it's about why you will be good at the job. What's in your experience or skill set that will equip you to tackle the job? What can you point to in your past that shows a track record of doing well at similar work? It's key to think about this question, because it will be the No. 1 thing on your interviewer's mind.
4. What will the challenges be? Every job has its challenges, and showing your interviewer that you're aware of and prepared for them will make you a stronger candidate. When you imagine being in the role, what do you imagine to be the most difficult or frustrating parts? How will you approach those or manage around them?
5. What is the company all about? How do they see themselves? While companies might all look relatively similar from the outside, internally they usually have a very clear self-image. For instance, they might see themselves as cutting-edge, conservative, zany, or warm and informal. Understanding how they see themselves will allow you to show how you'd fit in to their culture and their place in the market.
6. What are you most worried you'll be asked? Nearly everyone has something they're hoping their job interviewer won't bring up. For some people, it's why they left a previous job or if they've ever been fired. For others, any discussion of salary terrifies them. Figure out what you're most dreading, and practice your answer to it over and over. If you avoid it in the hopes it won't come up, you risk winging it if it does—and doing that on a sensitive topic is likely to produce an answer you're not happy with.
Alison Green writes the popular Ask a Manager blog, where she dispenses advice on career, job search, and management issues. She's also the co-author of Managing to Change the World: The Nonprofit Manager's Guide to Getting Results, and former chief of staff of a successful nonprofit organization, where she oversaw day-to-day staff management, hiring, firing, and employee development.