Make a list.
Create a list of potential interview questions that you anticipate that you will be asked. You don't have to be a mind reader to accomplish this. Conduct an interview search of common interview questions. Think back to prior interviews that you have been on, and the questions you've been stumped with. Check with your Alma mater's career preparation center for lists of job interview questions. Using all of these resources, write or type up your list.
Answer the questions.
Write the best answers you can, but be honest. For example, one difficult question that tends to come up is, "Tell me about a problem you encountered at your last job, and how you handled it." If you didn't have a big problem that you were able to solve, but you learned a solution from someone else, you could say "I can't think of one, but one problem I anticipate happens in this line of work is...and to remedy that, I would..." This is honest and shows that you do understand how to deal with stressful situations gracefully.
Practice answering these questions out loud.
You can do this sort of interview training in front of a mirror to begin with, so you can see exactly the mannerisms an employer will see. Practice giving your answers with a calm conviction in your voice. Your tone should be confident, but not aggressive or cocky.
Find a friend to role play with you.
Give them the list of questions, and ask them to ask you them in random order. Ask them to judge your mannerisms at the end, such as good eye contact, voice control, pausing instead of saying "um," and sitting straight.
Use positive self-talk.
Tell yourself that you've GOT this job as you sit in the waiting area before the interview. Look around as though you're getting to know the place, use good eye contact with people who come and go past you, thinking in your head "I'll be working with you soon." This pep talk in your head will help you with your confidence, which will be reflected in your answers. Often, how you say things is more important that WHAT you say. Following these steps will help you give the best job interview questions answers.
The key to any interview is preparation. You've worked hard to get the qualifications for the job, but doing well in an interview can be a completely different skill. Along with preparing job interview questions answers you need to remember why you were granted the interview in the first place. While it's true that these potential employers will be judging you, remember that they WANT to hire you! Otherwise they would not have called. Really think about all those reasons why they selected you in order to improve your confidence while you're waiting to be called in for your interview. Good luck!