Have you ever left a job interview knowing you could have done better? It is very easy to make mistakes during the interview and sometimes, you might not even know you made a mistake.

Thus, you will need to know how make a good impression to ace your interview if you are looking for a new job or planning to do so in the future. Mastering this art is not easy as most people do not go through them very often.

Here are 25 common mistakes made at a job interview. Read and hopefully, it will give you ideas what not to do in future.

1. Not taking the interview seriously
An interview isn't just for formality, treat every interviewer with respect. An interviewer will be able to tell if you are sincere about the post.

2. Dressing down or inappropriately
This is common sense and first impression counts a lot. It speaks volumes to someone who is meeting you for the first time. Even if the firm allows their employees to wear jeans, please do not sabotage yourself with a "casual Friday" dressing. If you are going for a corporate job, make sure your clothes are neat and professional.

3. Not knowing the location of the interview
Know your location and don't depend on your smartphone (Google Maps etc) to find the place. You do not want to be left stranded in an event you do not have any internet connection. Get ready in advance, print out the address or a map so you can avoid being late for your interview.

4. Leaving your mobile phone on
Not only it is disruptive but also rude to have your phone ringing halfway into an interview. Silent your phone before an interview.

5. Chewing gum
Chewing gum is unprofessional and may distract your interviewer, making it hard for him/her to focus on what you are saying. Also, as the interview questions become tougher, your chewing may become more aggressive due to nervousness. It is okay to have a mint or to chew a piece of gum but take the gum out before the interview.

6. Having a weak handshake
26% of job seekers made this mistake. A weak handshake indicates a lack of confidence in yourself. Keep your handshake firm.

7. Saying too much/ too little
Don't gloss over vital information, and don't go into too much details. It is a two-way conversation, try to maintain a balance between saying too much or too little. Be calm, listen carefully to the question and answer it thoughtfully.

8. Lying
You may sell yourself in the resume but don't oversell or lie about your experience or what your abilities are in an interview. If you don't know something or the answer, just let the hiring manager know. He/she will appreciate your honesty.

9. Poor posture
Present yourself well, don't hunch or sink into your chair. Sit upright and keep your back straight. A good posture sends good signals about your overall demeanour. Be careful not to come across as a stiff robot too.

10. Showing up late
Arriving late without a valid reason is telling your hiring manager that he or she isn't worth your time. If there is any emergency, call the company immediately to let them know. Reschedule the interview if needed.

11. Not being yourself
Don't focus on saying the "right thing" you think your hiring manager will like that you do not portray an accurate view of your skills and experience.

12. Fidgeting
Be conscious of your actions. Don't play with your fingers, clothing or hair when you are uneasy or nervous.

13. Not smiling
Nervousness can make you forget to smile but make sure you don't look unhappy or unenthusiastic about having this opportunity.

14. Not making eye contact
Not having eye contact with your interviewer will indicate you have something to hide. On the other hand, do not stare at your interviewer. You do not want to come off as creepy or mental.

15. Not having your portfolio handy
A portfolio helps the hiring manager see your overall experience and skills. Don't be caught without it.

16. Not having "hero" stories
Some interviewers will ask "How did you overcome this particular challenge in your old position". Be prepared to whip out your "hero" stories to demonstrate your competence but be careful to have a balance between showing your capability and bragging about your achievements.

17. Inadequate research about a potential employer
Learn as much as possible about your prospective employer so you do not appear dumb when you are stuck with a common question like "What do you know about our company?". Visit the company's website, learn about their people, their history and their mission. Familiarise yourself with the organisation and show your hiring manager that you are diligent and you care.

18. Not knowing the name and designation of the interviewer
Have a printed copy of the email asking you to come in for an interview. Write down the name, contact details and designation of the person in case you need to refer to it.

19. Not having a notepad and good pens
You may need to fill up application forms or take notes during the interview. A second pen is needed if your first pen runs out of ink. Impress the hiring manager by showing you are always prepared.

20. Mumbling
Mumbling indicates you are not sure of yourself and it will do you no good if your interviewer cannot hear what you are saying.

21. Not having your planner or fully charged smartphone
The interviewer may ask you to return a few days later for a second round of interview. A planner or your smartphone will allow you to commit and schedule that on the spot.

22. Trash talking
No trash talking or complaining about how your former boss is a piece of crap or your previous employer treated you unfairly. If you were fired or laid off, prepare an explanation and put a positive spin on it.

23. Focusing on what you want
You need the job but don't keep focusing about how much you want or what you need. Explain how the company can benefit by hiring you, be their solution.

24. Not preparing questions for the hiring manager
Asking the appropriate questions to show your analysis and situational understanding of the organisation. Hiring managers are reassured when you show intelligence by tackling pain points of the position such as "What contribution you'd like to see this person bring to the company?"

25. Failing to ask for the job
The interviewer may not have an answer for you at the end of the first session but do not be afraid to emphasize that the job is really what you want. However, do not appear too aggressive or desperate for it. Send a thank-you note or polite email after the interview to express your gratitude for his or her time and consideration.

101 Great Answers to the Toughest Interview Questions
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