Job interviews are usually your one-time opportunity to show an employer why they should give you a job over other applicants. So, you should want to make the best impression possible and show them that you can not only do the job, but that you can fit into the current team.

Of course, most of us do not fail at job  interviews by choice—it is simply the employer’s choice to take on someone else. However, there are things that you can do at job interviews that can jeopardise your chances – with or without you even knowing it:

Being late to the job interview

Although there may be some circumstances (like snow, major road accidents etc) that are beyond your control, for the most part if you plan your time properly, there should be no excuse for arriving late for your job interview.

Things such as traffic delay or being unable to find the employer’s place of business are acceptable. If you have allow enough time and plan to get there early, you will not be late.

Taking calls on your mobile phone during the job interview

Make sure your mobile is switched off before you go into the interview room. Don’t wait to be called in before you switch it off – do it while you are waiting at reception to be called in or, better still, just before you enter the building.

At no time is it acceptable to accept a phone call during a job interview or to provide the interviewer’s phone number to others. If you have children and know that you are expecting a phone call from them or childcare, make sure you speak to them before you enter the building and let them know that you will not be contactable for an hour or so.

If you start taking calls from the nursery during your job interview, for example, the interviewer will think you are unorganised, and who could blame them? Can they expect you to act this way when you are in meetings with an important client? Or while serving customers?

Dressing inappropriately for a job interview

Is it ever acceptable to ear jeans to an interview? Not unless you are the one doing the interviewing…and even then it doesn’t speak to well of you as a professional. Wearing jeans, shorts or other casual attire shows a level of complacency that you should avoid at an interview. If the environment you are going to work in is known for smart casual clothing, then you can wear smart trousers instead of jeans, for example, that still looks trendy, but shows that you are serious about the job.

Discussing personal affairs with the interviewer

Although the interviewer may ask you a series of personal questions during the job interview, do not offer any information that is not directly related to the job. If you don’t drive, for example, he may ask how you will get back and forth to work if there is no public transport and you can say that your husband or partner will drive you to and from work on route to his own workplace – there is no need to discuss other issues.

The interviewer doesn’t care if you are buying a new house, getting married next week, or having problems at home. And if you offer too much insight into your personal challenges during a job interview, it could put them off.