What are some tips for staying calm during a tough interview?

Recognize why you're there.
Be confident in your abilities
Do a job interview mock run.
Find a quiet space, preferably with a mirror, and interview yourself. While you are practicing the interview you may discover topics or questions that you do not have a ready answer for. Make note of these questions for later consideration and research. If your practice space has a mirror, be sure to note your facial expressions in order to catch any out of place expressions that may make you appear as if you are not staying calm. Job interviews, being a time of stress, can cause people to show a little more stress than they’d like to show.
Plan ahead.
Stay on target.
Your goal at the interview is to open up in a way that's captivating
Do your research.
Be an active listener.
While it's always beneficial to rehearse an interview beforehand, it's just as important that you stay actively engaged during the interview
Pace yourself.
Just as it's important to begin your interview with energy and enthusiasm, it's also important to carry that forward to the very end

Here are some helpful hints about staying calm during a tough interview:
1. Advance Preparation: Know your strong points so that during the interview you can speak about them in a calm manner, without them asking you. If this is done it will leave a positive impression in the recruiter's mind. Your strong points should be discussed by relating them to what this particular job has asked for and what you could bring to the company. Research the company so that you can ask the right questions when it is time for that. If you know about this company you will make another good impression. You will also feel more comfortable and calm in the HOT SEAT because you are prepared and knowledgeable about yourself and the company. (THIS COULD GET YOU THE JOB.)
2. Honesty: Interviewers are very intuitive about honesty and dishonesty. It is important that you answer their questions with honesty. If you want to get their attention be honest (do not lie about the answers, it usually gets you no where). When speaking try not to clear or throat all the time because you are nervous, but answer in a clear and concise way. Give straight forward answer and don't say any more except you might want to give one of your strengths at this point, but let them ask you more about those strengths so that they feel in control of the interview.
It is Calming to know and feel good not fudging or lying in the answer.
3. Practice Answering Questions: There are many books and online questions for you to practice interviewing with a friend. Look up those questions, write down yours answers and then practice answering them to someone you trust to give you feed back for your answers. A few Questions to practice would be: What is your best skill and what do you need to improve on?; Have you had a ever solved a problem that occurred between two other employees and how did you solve that problem?; Why do you want to work for this company?; Describe you ideal career?; Tell me something about yourself that I don't know from reading your resume?; Tell me what you know about this company?
What would you done differently if you were to run this company? (How to find out if you research this company);Do you believe you are overqualified for this position and why?; Why do you want to leave your current job? What salary would you expect for the job?; (Use the salary.com site or some other site to find out what the salaries are for the position that you applied for?). What new skills or ideas do you bring to the job that other candidates aren't likely to offer? If you can practice answering these and other questions you will feel so much calmer then you would if you don't practice. The practice gives you confidence and that will give you strength to get through the interview with flying colors.
Illegal or stress Questions: These questions are shock questions and some interviewers will ask these to see how you might react. If you sit for a few seconds and get your thoughts in order you will answer appropriately. They are trying to see how you react with pressure and tension on the job. So prepare for these and don't act defensive but with confidence. If you simply can't answer the question smile with confidence and without apology, but simply say
"I can't answer that question." Know what some of the illegal question are and be ready. Some illegal questions are regarding Age, religion, number of children, married etc.
Telephone Interviews: These are becoming more commonplace because companies want to reduce their hiring cost by avoiding travel at careening stages in interviews. They can quickly weed out most candidates and decide on the best to pursue. Practice with a friend over the phone. You can also listen to yourself and your own voice by leaving a message on your answer machine. You will be more confident about how you sound to others and if you need to change the tone or speak slower or faster.
On your way to Interview: Although Preparation is important, your performance during an interview can make an even greater difference. Generally keep in mind the following qualities in your choice of words, tone of voice, and body language: Capability, Confidence, Dependability, Calm manner, Enthusiasm, Flexibility. All of these characteristic should be shown in the interview process and if you have prepared properly with all the above suggestions you should feel calm and confident to be able to answer everything that they are asking and showing them your best qualities.

**If you are well prepared you will be able to make a good impression with your answers. My Motto is BE PREPARED FOR ANY AND ALL QUESTIONS THAT ARE THROWN AT YOU AND ANSWER WITH CONFIDENCE
AND CALMNESS! If you are prepared you will exude the confidence needed.

Good Luck to you and just remember to PRACTICE: P=PREPARE; R=RESEARCH; ACCOMPLISHMENTS; C=CONFIDENCE; T=TIMING; I=INTERVIEW; C=CALM; E=ENTHUSIASM. THE MORE YOU PRACTICE THE CALMER YOU ARE!

YOU CAN DO IT!!!

Hi Kira,

Here it is some tips that can help you:

1. 
   

   Don't speak too fast
   Nerves tend to make us speed up, so while you're waiting for your interview, breathe in through your nose very slowly for a count of three. Then breathe out through your nose for a count of three. Repeat this three times. That should take you a total of 18 seconds. In that time you will have significantly lowered your heart rate and when you speak, you'll find you won't rush.

   
   


2. 
   

   Stop yourself shaking
   Simply squeeze your buttocks or your thigh muscles. It's almost physically impossible to have shaky hands if your buttocks or your thigh muscles are clenched. This technique will help you feel and appear more confident – and most clothes will completely mask your actions.

   
   


3. 
   

   Stop your voice shaking
   Open your throat by sticking your tongue out as far as it will go, and try to say the whole of the Humpty Dumpty nursery rhyme out loud. This will open the back of the throat and you'll sound more confident and have more authority. Of course, you should do this before the interview – not in front of the panel.

   
   


4. 
   

   Stand up while you wait
   You will often be shown into a boardroom before an interview and offered a seat while you wait. Don't take it. You don't want their first impression of you to be struggling up out of a chair, so stay standing. You'll look more confident if you are on their level as you first meet them.

   
   


5. 
   

   Find your best sitting position
   Firstly, never trust the back of a chair. You can easily end up leaning too far back which can tighten your throat. I recommend leaning slightly forward on your chair. You'll look and feel more dynamic if you sit in this position.

   
   


6. 
   

   Show your hands
   It has been proved that we are much more likely to get a job if we have our hands visible on the table in front of us rather than hiding our under the table. Showing our hands is a sign of honesty.

   
   


7. 
   

   Make the other person feel special
   Many people try too hard in a job interview and end up merely bigging themselves up. We have all been bored by other people going on about themselves without being the slightest bit interested in us. Remember to ask questions – and be genuinely interested in the reply. Obviously it's important to look keen and passionate about the job on offer but try not to simply blow your own trumpet too much.

   
   


8. 
   

   Listen
   When we're crippled with fear and in full flight or fight mode, we find it hard to listen and often answer the wrong question. So try to slow down your body's natural responses and listen – it will also help to make the other person feel special and show you value their question.

   
   


9. 
   

   Use your own voice
   Try to use your own voice rather than putting on a formal public speaking voice. Often this is as simple as not speaking too loudly. Speak as if you were talking with a group of friends.

   
   


10. 
    

    Be yourself
    If we are being ourselves when meeting other people, we will come across as relaxed, authentic and confident.

    
    

By Robin Kermode is author of Speak So Your Audience Will Listen – 7 steps to Confident and Successful Public Speaking

In: https://www.theguardian.com/careers/careers-blog/10-quirky-tips-beating-interview-nerves-job

Best of Luck!

Here are the tips :

1. BE KIND TO YOURSELF PRIOR TO AN INTERVIEW:

It’s essential to do a self talk with compassion, similar to a best companion, and put forth any critical thoughts that stand in your path, states Connell. He advices not to be hesitant to sell yourself. Individuals stress over seeming arrogant, however, the interview board aren’t mind readers and don’t consequently comprehend what you bring to the table, so it is dependent upon you to let them know.

2. SEE YOURSELF SUCCEEDING:

Envisioning yourself being successful at a forthcoming job interview will give a lift to your confidence levels and increase self-esteem. Before you go in begin envisioning a successful interview: envision how you stroll to the room, shake hands with the interviewer and answer the questions with confidence. According to Margaret Buj, interview coach and writer of Land That Job!. This strategy will help to quiet any pre-interview nerves.

for more details: Interview Preparation For Freshers

Preparation and practice! The more prepared you are the easier it gets. I wrote an article about general preparation for programming interviews, since last year I went through several:

https://codepointers.com/2017/10/08/changing-jobs-interviews/

But the end section is focused on being in the right state of mind before and during the interviews, which is not programming specific if that's not your field. Since then I've also started doing meditation, which is generally very helpful for managing stress and nerves.

Hope this helps!