I’ve conducted hundreds of job interviews in my career. To this day, I’m still surprised by the number of mistakes interviewees make, turning an opportunity to shine into a pointless waste of time for me and for them.

Here are the five most common interview mistakes I’ve seen and advice for how not to make the same blunders.

Common Interview Mistakes to Avoid

Mistake 1: Not Doing Your Homework


If you show up at an interview without a fundamental understanding of what a company does, it’s hard to take your interest in the job seriously. Why should an employer trust you with important work when you couldn’t be bothered to learn who they are?

Spend time on the internet absorbing all you can about your potential employer. If it’s a larger firm, read press releases to get an understanding of major events from the last year, and find ways to ask about those events in the interview. If it’s a public company, go to places like Yahoo Finance and read what analysts are saying about the enterprise. Research the company’s competitors and be ready to ask how the organization differentiates itself from the rest of the market.

These small things are relatively easy to do and show a level of interest that will impress the interviewer every time.

Related: 9 Tips for Mastering Your Next Virtual Interview

Mistake 2: Asking About Pay or Benefits Before an Offer Is Made


I was once interviewing a woman for a job in a startup that had just gotten going. The interview was at 7 p.m., and the office was still buzzing with employees as we scrambled to get a product launched ahead of a competitor. Not 15 minutes into our discussion, she asked me how much vacation she would get and if she could leave early two days a week.

Needless to say, she wasn’t hired. I’m not saying everyone who worked for us had to commit to a 60-hour week, but the timing was off. Don’t ask about benefits until you have an offer in hand. It implies the job is more about you than the team. And don’t ask for a modified schedule until you’re closer to securing a job offer.

Most employers today are happy to do flex arrangements. But most are not interested in fielding that request during a first-round interview.

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Mistake 3: Making the Job About Advancing Your Career


Don’t make your resume, or your interview, all about you. That may seem strange, since a resume is, by definition, “all about you,” but I’m talking about statements people put under a heading like “Objective.”

Avoid objectives or stated goals that are too self-centered, like, “I want to find a job where I can advance my skills in marketing so I can, one day, lead a marketing team.” No matter how employee-focused a firm is, they’re hiring you to advance their mission and financial objectives.

Make your objective about them. Instead, write, “I hope to use the skills I’ve developed in marketing to make Acme.com build a larger prospect funnel.” That will be music to an interviewer’s ears.  And if you do your job well, you’ll get that promotion to lead a team in due course.

Mistake 4: Not Writing a Thank You Note


There is controversy in the HR world about this. Many say writing a thank you note isn’t necessary, but I still feel strongly about it.

Writing a thank you no longer means a longhand note and trip to the post office. Fortunately, email is sufficient today and so much easier. And because it’s easier, there’s absolutely no excuse for not doing it. It’s polite and reminds the employer of your interest.

If done well, it also gives you an opportunity to review what you learned in the interview, which can help you stand out from the crowd. Even if the note isn’t your best piece of work, it can help propel you to the front of the line, over candidates that didn’t send a thoughtful post-interview message.

Related: How to Properly Follow Up After a Job Interview

Mistake 5: Not Answering Questions with Specificity


You may have heard you should include metrics in your resume to illustrate achievements. It’s not good enough to say, “Improved invoice handling process.” Instead, say, “Reduced invoice handling costs by 12%, saving $50,000.” The same goes for the interview. Be specific.

Numbers in stories make them more believable (but don’t lie about the numbers!). In addition to having metrics at your fingertips, be sure to clearly explain what you did to drive the results.

Finally, when appropriate, acknowledge when you were part of a team and give your colleagues some of the credit. When someone says, “I did this” and “I did that” over and over, they may come off as arrogant and, perhaps, send a signal that they’re not a team player. Language matters and precise language can communicate things that are hard to convey in a short meeting.

Preparing for Your Next Interview

If you have a job interview coming up, remember that preparation is key. Stepping into the meeting armed with company facts, and the appropriate talking points, can put you one step closer to landing the job. In the end, success in a job search is closely related to the things we learned when we were young: be conscientious, be humble, and say thank you. It really is that simple.

Are you interested in additional career development advice? Explore our posts on “Questions You Should Ask the CEO” or “A Cheat Sheet to Answering Common Interview Questions.”

Patrick Mullane

About the Author

Patrick Mullane is the Executive Director of Harvard Business School Online and is responsible for managing HBS Online’s growth and long-term success. A military veteran and alumnus of Harvard Business School, Patrick is passionate about finding ways to use technology to enhance the mission of the School—to educate leaders who make a difference in the world.