Interview Success - You Only Get One Chance to Make a Good First Impression

The key to a successful interview for a job is etiquette and preparation. There are some rules to interviews that should always be followed:
What to wear: Dress neatly and more conservatively than you normally would. Your dress says a lot about you and how much you care about the job.
Timing: Never be late for an interview. Arrive 10 or 15 minutes early to allow for any problems in getting to the location.
Body Language: This says a lot about your level of interest in the interview. Maintain good eye contact, posture, and avoid doing any distracting movements.
Listen & Talk: Show that you are interested in what the employer is telling you and use what they are saying as a way to evaluate whether the job is right for you. When it is your turn to do the talking, speak naturally and take advantage of opportunities to ask your own questions or initiate new conversation.
Answering Questions: Reply to questions with direct answers, do not try to avoid them. Take the time to collect your thoughts and if you are unclear about the question, ask for an explanation. If applicable, use examples of your accomplishments in your answers.
Interest Level: Always maintain a high level of interest in what is taking place, both through your composure and your voice. Come equpped with pen & paper to take notes and bring a few more copies of your resume.
You should first be able to easily discuss your skills, abilities, and personal qualities. Secondly, you should have a solid background on the organization and the position you are applying for.
There are several categories of questions that are commonly asked in interviews. If you are well-prepared for these questions, you will be composed and confident.
Self Assessment and Career Path

How do you describe yourself? How do others describe you?

What are your short and long-term goals?

What are your strengths and weaknesses?                 

Why should I hire you?

Academic Assessment

How has your education prepared you for a career?

What led you to choose your field of study?

Tough Questions

How did you get along with your last boss?

What is the hardest job you have ever had?

Familiarity with the Employer

What do you know about this organization?

What contributions do you think you could make here?

Other Interests and Experiences

What accomplishments have given you the most satisfaction?

What problems have you met and how did you deal with them?

An interview is not only about being asked questions and answering them. It is important that you ask the questions too! This shows that you are informed, responsible, and prepared. 
Questions to Ask the Interviewer

What are the reputations, training, and tenures of the employees at this organization?

How do you support professional development?

What are the goals of the department?

What is the work environment like?                 

You should not be the only one evaluated after an interview; you should also be evaluating the company or organization to make sure that this is a place that you would want to work. Make sure that all your questions were answered and make sure to send a thank-you to the interviewer as soon as possible.