Here are five interview mistakes that you can avoid if you know about them ahead of time.
1. Not preparing. This is probably the No. 1 mistake most job candidates make: They show up for the interview without thoroughly preparing in the days before. Preparation doesn't mean a quick skim of the job description and a glance at the employer's website; it means at least several hours spent thinking through likely questions and practicing your answers to them, as well as thinking back on specific examples you can pull from your past to illustrate how you've excelled in previous jobs.
2. Not researching your interviewer. A quick glance on LinkedIn might give you advance warning that your interviewer used to work with that old boss who hated you, meaning you won't be caught off guard if asked about it in the interview. Or simply reading your interviewer's bio on the company website might tip you off that she has a background in the software you used to work with and you might get a lot of questions on that.
3. Being late. You might think that you're playing it safe by leaving for your interview a few minutes earlier than you need to. But hit a traffic accident and that buffer will fly out the window, which means you could end up arriving late. When you're heading out to an interview, it's smart to give yourself a huge buffer—meaning an hour or so—because it's nearly impossible to recover from being late for an interview. You can always kill the extra time in your car or a nearby coffee shop if you arrive early.
4. Wearing the wrong outfit. In most industries, you should wear a suit to a job interview. (IT is sometimes, but not always, an exception.) It doesn't matter if your interviewers are more casually dressed themselves; wearing a suit, as the candidate, is still an expected convention typically. But aside from picking out the right clothes, you also need to make sure that you look polished and groomed—that your clothes fit you well, that your hair is neat and in place, that your makeup is professional and not heavy-handed. It's also key that you feel comfortable in whatever you're wearing; you don't want to be constantly adjusting your neckline or fidgeting with your cuffs.
5. Not being ready to talk about salary. Job seekers are often more uncomfortable with conversations about salary than anything else, and as a result, they often don't prepare for how they'll handle questions about it. This is a huge disservice to yourself. If salary does come up and you try to wing it, you're likely to end up with less money in your offer than if you were prepared. So don't leave it to employers to manage salary discussions for you; do your research and thinking ahead of time so that you can field salary questions confidently.
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.