There are some things you should never do during an interview, yet I see people willingly doing or saying the dumbest things during an interview process. While I can think of a long list of suggestions of what you should do, let me suggest some of the most basic and potentially damaging things you should never do during an interview.
Never go to an interview without having done some research or without having at least a basic understanding of the company or organization. With the internet as a resource, there’s no excuse for not being prepared and, in almost every interview situation, you will be asked either what you know about the company or what it is about the company that interests you.
Never assume that you are the only person or candidate being considered for a particular position. You are among others seeking the same job, no matter how good you think you might be. Confidence is fine but expectation and an air of entitlement are the fastest ways to eliminate yourself from the process. Ironically, the result could be that you’re the most qualified person who didn’t get the job.
Never speak badly or in a derogatory tone about your past employers, the company for which you most recently worked, or other persons with whom you have worked. It’s never favorably looked upon. It isn’t the type of information that will impress or earn you a new opportunity. Getting personal or complaining serves no purpose and will be more likely be regarded as excuses and offsets any good points you might otherwise make. You’ll be demonstrating why you are the wrong person for the job. It may rightfully lead the interviewer to conclude that if you speak that way about others with whom you’ve worked, then you’re likely to do the same later about the job for which you’re currently applying. Reasons for departing a previous job should be described professionally, without getting personal.
Never dump your personal problems on an interviewer. They do not have one ounce of interest or responsibility for any of your personal issues. When you go to an interview, leave your personal problems at the door. If a subject of this nature comes up, keep your responses to a minimum and focus instead on the job, your qualifications and abilities.
Never assume that the final interview, or any interview for that matter, is just a formality and you already have the job. There is no such thing as a rubber stamp interview. Until you sign a written offer you are not finished demonstrating why the job should be yours. Until you sign the job offer or contract there are no unimportant steps. I have known many people who ruined their chances and blew it on the final step of the process.
The dumbest wounds are those that are self-inflicted.