7 mistakes you should never make during a job interview, according to a business-etiquette expert
Common Interview Mistakes That Can Cost You the Job — and How to Avoid Them
For many professionals, job interviews are among the most stressful steps in the hiring process. Even well-qualified candidates can underperform due to avoidable missteps. To help job seekers put their best foot forward, Business Insider consulted business-etiquette expert Jacqueline Whitmore, who outlined some of the most common interview mistakes she sees — and how candidates can avoid them.
1. Showing Up Unprepared
One of the most frequent and damaging mistakes candidates make is failing to prepare adequately.
According to Whitmore, many applicants do not take the time to research the company or the interviewer, despite having abundant resources available. Company websites, LinkedIn, and social-media platforms offer valuable insights that candidates should review in advance.
“There’s no excuse for going into an interview without knowing about the company or who might be interviewing you,” Whitmore explained.
Preparation also includes asking thoughtful, company-specific questions. Doing so demonstrates genuine interest and shows that you have invested time in understanding the organization.
2. Dressing Too Casually — or Ignoring the Details
Another common error is underestimating the importance of professional appearance. Whitmore notes that candidates are rarely overdressed for interviews, but they are often underdressed or careless with details.
Small oversights — such as mismatched shoes and belts, visible clothing tags, or unopened suit vents — can send the wrong message.
“Why would an employer want to hire someone who doesn’t pay attention to details?” Whitmore asked.
Your appearance should reflect professionalism, polish, and respect for the opportunity.
3. Overlooking Your Social-Media Presence
Before an interview even begins, many employers will search for candidates online. Whitmore emphasized that social media often shapes first impressions.
Employers may review what you post, who you associate with, and how you present your lifestyle. These details can influence hiring decisions, consciously or unconsciously.
To avoid issues, Whitmore recommends reviewing privacy settings and removing any content that could be perceived as unprofessional or inappropriate.
4. Using Filler Words, Slang, or Inappropriate Language
Clear and professional communication is critical during an interview. Whitmore cautioned against using profanity, slang, or industry jargon that the interviewer may not understand.
She also warned against overusing filler words such as “um,” “like,” or “you know,” which can weaken your message and distract from your qualifications.
Practicing aloud or recording yourself before the interview can help improve clarity, confidence, and precision.
5. Keeping Your Camera Off During Virtual Interviews
In virtual interviews, refusing to turn on your camera can be a red flag. While candidates may feel uncomfortable being on video, Whitmore said facial expressions and body language play an important role in communication.
She also advised candidates to be mindful of their surroundings. A clean, simple background — even a blank wall — is preferable to a cluttered or distracting environment.
Putting thought into your setting demonstrates professionalism and preparedness.
6. Arriving Late
Punctuality remains a fundamental expectation. Arriving late, even by a few minutes, can significantly harm your chances.
“Showing up late for an interview is a huge no-no,” Whitmore said. “When you’re on time, you’re still late. You should show up early.”
Arriving early allows time for parking, locating the interview room, using the restroom, and mentally preparing before the conversation begins.
7. Failing to Send a Thank-You Note
Many candidates underestimate the impact of a follow-up message. Whitmore strongly encourages sending a thank-you email — and, when appropriate, a handwritten note — within 24 hours of the interview.
This follow-up is another opportunity to reinforce your interest and qualifications.
Address the interviewer by name, reference specific aspects of the conversation, and briefly explain why you would be a strong fit for the role. If you are unsure how to phrase it, drafting a note and refining it with an AI writing tool can be a helpful approach.