The worst thing you can do on a job interview

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You won't believe what one job candidate had hidden in his shirt. It was a bad idea, and he didn't get the job.

A good first impression can improve your career — and you have just five minutes to make one in a job interview.

That's how long it takes half of hiring managers to figure out whether a job candidate would be a good fit for a position, according toa recent CareerBuilder survey.

"Interviewers gather clues about you based on whether you are punctual, how you are dressed, your handshake, the eye contact you make and the first words that come out of your mouth,"said Rosemary Haefner, chief human resources officer forCareerBuilder. "That's why it's important to have a strategy for a great first impression every time you interview."

Now is a particularly good time to figure that out as the job market shows signs of improvement. December ended with a 292,000 gain in total nonfarm payroll employment, according to theU.S. Bureau of Labor Statistics. And 2016 is poised to be even better.

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"The good news is that we ended 2015 with a near-record number of job openings, giving workers added comfort to move forward with plans to improve their current positions and find different opportunities," said Haefner.

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Still, don't expect the job hunt to be easy. While opportunities abound, competition for them is fierce.

"Organizations are much more particular," said Kim Seeling Smith, founder of human resources training and consulting firm Ignite Global. "We went through years of cost cutting and headcount reduction, so when they hire, they want to make sure they hire the best person. Employers are being more picky, so it's really critical to nail the interview."

For starters, don'thide your pet bird in your shirt during an interview. It sounds ridiculous, but that's just one example of a supremely strange job interview, according to the CareerBuilder survey. Hiring managers also reported a candidate stealing a family photo off of the interviewer's desk, another candidate screaming that the interview was taking too long and when asked why he wanted the position, a third candidate said, "My wife wants me to get a job." (No points were awarded for honesty.)

While those examples are extreme, being guilty of simpler faux pas, such as bad body language, can also be harmful to your job prospects. Not making eye contact was the most common job-interview error with 67 percent of hiring managers identifying it as the biggest body language mistake. Not smiling, playing with something on the table, bad posture and fidgeting too much are also bad job-interview behaviors.

Beyond body language, career experts say to avoid a number of other mistakes that will ruin a job interview. The top way to guarantee you won't get the job? Get caught lying about something, which 69 percent of employers deem an instant deal breaker.

Answering a call or text during your interview is another huge no-no, with 68 percent of hiring managers reporting it as a problem. Appearing arrogant or entitled ranked third among job-interview deal breakers.

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On top of avoiding these mistakes, you need to prepare well in order to ace your next interview, Haefner added. "Due to technology, job candidates have all the information they could need at their fingertips through a web search," she said. "Because of this, companies now expect you will do your due diligence before your interview more than ever."

Seeling Smith recommends finding out who will be conducting the interview and "LinkedIn stalking them." Learn about their background and current job title and figure out whether that person would be your supervisor or simply among the people you might work with, she said.

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Also find out as much as you can about the actual role you're applying for. Try talking to someone in human resources before your interview to learn the three key attributes that the hiring managing is seeking from the right candidate and the three main goals she wants this position to achieve. "Then it's your job to come up with examples of where you have been able to deliver something similar in the past," said Seeling Smith.

Of course, you need to be prepared to answer common interview questions, too. Seeling Smith suggested practicing your answers in advance and keeping your responses between 30 seconds and two minutes.

Finally, don't forget that a job interview is a two-way street. You're not only trying to prove that you are the right person for the job; you also want to figure out if the position and the company are a good fit for you. So ask questions about the role (not about compensation at this point), such as why it exists, how it impacts the company and how success is measured.

Your questions can help you get answers and make you a more appealing candidate at the same time. Since people often make the mistake of neglecting to do this, asking good questions during an interview is a great way to stand out from the hiring pool

"Interviewers learn as much or more about the candidates that they're interviewing by the questions that the candidates ask than by the answer they give to the interviewers' questions," said Seeling Smith.

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