I sat in traffic in Boston, Massachusetts one cold autumn morning 16 years ago, cursing myself, cursing the cars around me, and cursing the world.

I had prepared so much for the job interview at the prestigious firm I was driving to - done research, gotten dressed in a sharp outfit, prepared questions to ask - and yet somehow I had not left enough time to make up for a traffic jam on the way to their offices.

I arrived 15 minutes late, and had what I thought was an excellent interview - but of course I did not get offered the job. I may have been a pretty smart, determined guy, but what a stupid mistake I made that day, to not leave enough time to get to the interview early.

I've written before about dressing appropriately for a job interview, and asking the right questions. Of course, there's much more to a job interview. And showing up late may seem like a pretty obvious mistake, but as I talked to other leaders, I couldn't believe some of the mistakes I heard people making.

Below is a list of mistakes to avoid at job interviews - all, believe it or not, based on real stories shared with me by members of the Young Entrepreneur Council (YEC), an invite-only organisation comprised of the world's most promising young entrepreneurs. Don't make the same mistakes these people made!

1. Trashing a Boss or Old Job

I get it. You had a horrible boss who ruined your experience, and now you are leaving. You may be bitter or angry, but don't let that unhinge you in a professional setting. You don't know if I know your boss, or how I will react. Was it you or them? I'd rather see someone who can learn from tough experiences and hold their head up high. Don't avoid the question if asked, but handle it with class.

- Trevor Sumner, President and Co-Founder, LocalVox

2. Taking a Call or Checking Messages

In China, a lot of the people we interview have the habit of doing this in interviews. I have no problem if the phone rings, but it is what the person does after that lets me know how that person would treat a client in a stressful situation. They don't know this, but I actually analyse everything they do to determine if it would make a customer feel uncomfortable or not.

- Derek Capo, CEO and Founder, Next Step China

3. Drinking a Beer

I couldn't believe it. On a Skype video interview, a candidate who was great on paper moistened his lips with a beer before starting to talk. He took several more sips throughout the then-shortened interview, and I told the employee who was supposed to screen after me not to bother. We closed him out.

- Ryan Buckley, COO & Co-founder, Scripted, Inc.

4. Over-Selling Yourself

Job interviews can be nerve-racking, and it's normal to feel the need to "sell" yourself. But some candidates get so focused on selling themselves that they forget to ask questions to learn if the job is even a good fit for them in the first place. Or worse, they come off as disingenuous, inauthentic or fidgety. Interviews should be a conversation, not a sales pitch.

- Matt Ehrlichman, CEO, Porch

5. Underdressing

One time a potential hire called and asked what the dress code for the office was. We said casual. Then later that day, that person came in wearing a T-shirt, shorts and sandals. To me, a first impression is everything, and the fact that this person wouldn't even dress up a bit for an interview showed me that he was not a good fit for us.

- Phil Laboon, President, Eyeflow internet Marketing

6. Not Preparing Anecdotes

It's all about the evidence - saying you have a certain skill set or experience isn't enough, and anecdotes and examples are critical in showcasing that you really do have expertise. In particular, it's important for applicants to have quantitative evidence for any skills or experience they have. Without stories and numbers, an interview isn't as memorable or effective as it could be.

-Doreen Bloch, CEO / Founder, Poshly Inc.

7. Saying They Didn't Want to Learn or Work Too Much

I was interviewing a potential candidate who said to me, "My old job had me working and learning too much." This was after a phone interview where I explained we were a start-up! Start-ups are small, nimble, constantly growing and always learning to do things faster and better. This statement showed me someone who isn't ready to fully immerse themselves in the start-up mentality and culture.

- Kim Kaupe, Co-Founder, 'ZinePak

8. Crying

Yes, believe it or not, tough interview questions can make some people cry. When tears flow, the interview is over. No one wants to hire people who can't control their emotions on the job. I've interviewed over 1,000 people during the past 12 years, and in my humble opinion, crying is the kiss of death.

- Robert Sofia, Co-Founder & COO, Platinum Advisor Marketing Strategies

9. Being Unprepared

It's so hard to watch someone squirm during an interview. So many candidates think that they will waltz in, deliver a few canned responses and charm the pants off of their interviewer. It's not that easy. Candidates should know about the history, culture and brand of the company they are interviewing for.

- Maren Hogan, Chief Marketing Brain, Red Branch Media

10. Talking Themselves out of the Job

So many people go into a job interview and set themselves up for failure. Whether it's self-deprecating talk or downplaying their skill sets or just completely talking themselves out of the job, there is self-sabotage all over the place. If you're showing up for an interview, show up, be confident, be prepared, and rock it. You ARE amazing and deserve the job. Now go get it!

- Erin Blaskie, CEO, Erin Blaskie, Digital Strategist

11. Hedging Bets

The worst mistake you can make is hedging your bet. You are interviewing for a specific position within a company; therefore, you should focus on communicating your qualifications for that role. If you mention that "you are also available for consulting work," you don't seem very interested in filling the role you are interviewing for. In fact, you seem uncertain of yourself.

- Chris Hunter, Co-Founder, Phusion Projects

12. Having a Know-it-All Mentality

If I'm starting out a potential employer relationship with somebody, I want to make sure they're going to be a team player. People who think they know it all and/or are rigid in their beliefs can be very hard to work with. A know-it-all tends to accept that they do in fact know it all and won't change when they should really be constantly learning.

- Andy Karuza, CEO, Brandbuddee

13. Asking the Wrong Questions

I had an interviewee stop me in the first couple minutes of an interview to tell me her requirements for vacation. I can appreciate vacation time being important to someone, but I'm interviewing someone who I hope wants to work - not just take time off.

- Sam Saxton, President, Salter Spiral Stair and Mylen Stairs

14. Saying 'Yes' to Everything

When candidates say, "Yeah, I can do that," to almost everything that is asked during an interview, that's a red flag. The reality is they're thinking more about paying their bills or gaining employment than about what the organisation is trying to solve by hiring for the position. Some people have been searching for a job for so long that they're desperate to show they can handle anything.

- Brett Farmiloe, Employee 01: Digital Marketing Auditor, internet Marketing Agency

15. Focusing on the Benefits Over the Value

I've had people ask about benefits such as vacation time and paid time off right at the beginning of the interview. While it's important to have a clear understanding of all incentives offered, focusing on benefits offered by the company over the value they can bring to the company sends a message that the person is looking to take more than give.

- Michael Mogill, President, Crisp Video Group

16. Lacking Company Research

The worst mistake I've seen someone make at a job interview was not researching my company beforehand. It was so easy to tell, especially when I started asking questions related to our products. An hour's research can mean the difference between getting the job and wasting a company's time.

- Ted Murphy, Founder / CEO, IZEA

17. Not Having an Agenda

Most people show up to job interviews with the sole purpose of answering questions. Big mistake. It's imperative to have an agenda. For example, if you only communicate three key points about your experience during the interview, what must they be? If you'd like to display your knowledge of the company and the industry, have examples ready to go. Take a proactive approach.

- Antonio Neves, Founder, THINQACTION

18. Confusing Us With Our Competitor

I once had an applicant forget which company he was speaking with during our interview. About five minutes into our telephone interview, he started mentioning all the reasons why he wanted to work for our competitor. We obviously didn't invite him back for another interview. I didn't see any reason to embarrass him, so I just thanked him for his time. He probably never realised his mistake.

- Chuck Cohn, Founder and CEO, Varsity Tutors

19. Not Having Passion

Recently, a prospective hire fresh out of college applied for a job opening with us. During the interview, he showed a lack of research on the company. When I asked him what he was looking for in his career, he told me anything that hired him and paid well. The only enthusiasm in the whole interview was the possibility of earning a paycheck. Needless to say, we never called him back.

- Fehzan Ali, Co-Founder & CEO, Adscend Media LLC

20. Making the Interview Too Much About You

When interviewing, you're proving you can both do the job and bring value to the company. So don't focus on how great the job will be for you or your career. It's not about what you need at this point; it's about what you have to offer and what you bring to the table.

- Susan Strayer LaMotte, Founder & Principal Consultant, exaqueo

21. Making a Pitch on Autopilot

Interviews fail as soon as the conversation goes into autopilot. Interviewees should engage in a genuine dialogue starting with developing an informed understanding of the company and the person they're meeting with. Responses should be phrased within the context of the company, and the opportunity and questions should be real, not canned.

- Christopher Kelly, Co-Founder, Principal, Convene

22. Not Taking Ownership of Mistakes

I love to grill potential employees on conflict in their previous positions, and I always listen closely to how they describe what happened. I look for people who take full ownership and proactively look back at what they could have done differently. The worst mistake is just blaming others and not seeing how they played a role in the conflict.

- Laura Roeder, Founder, LKR Social Media

23. Asking What the Company Does

Every now and then, there are candidates who may have applied to several companies and are in the process of interviewing with many of them. They show up to an interview asking what our company does without having done any homework on the culture, position or mission of our organisation. We want to know we're bringing on people who are diligent, passionate and hardworking.

- Shradha Agarwal, Founder/Chief Strategy Officer, ContextMedia

24. Not Having Any Questions

At the end of most interviews, the interviewer says, "OK, so do you have any questions for me?" The absolute worst mistake a candidate can make is to say no. Really? Not one question? This immediately tells me they're not passionate about the job. They're not even interested.

-Marcos Cordero, Chief Gradsaver, GradSave, LLC

25. Wearing a Costume

During a one-way video interview, an applicant wore a Jedi robe (you know, as in Star Wars Jedi). The worst part was that the candidate made no reference to the costume at all. We were all baffled!

- Heather Huhman, Founder & President, Come Recommended

Some of these mistakes may seem silly or obvious, but they're all worth thinking about as you apply for your next job. It's worth avoiding the obvious mistakes, such as my lateness to that job interview 16 years ago, so that you can truly shine at every interview.

Now it's your turn. Have you ever made one of these mistakes? Let us know in the comments below or continue the conversation on Twitter @newscomauHQ

Dave Kerpen is the founder and CEO of Likeable Local. He is also the co-founder and Chairman of Likeable Media, the host of the Likeable Podcast, and the New York Times best-selling author of Likeable Social Media, Likeable Business, and Likeable Leadership. This article originally appeared on Linked In.

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