Four mistakes stand out as the ones most commonly made by candidates interviewing for a position. In order of importance, they are:

A. Losing sight of the interview objective.
The objective is to get the job offer. This can't be over emphasized. If you lose sight of this objective, be prepared for the unpleasant consequences because the offer will likely go to someone else. Don't let your preliminary judgment of the company affect your interviewing technique and strategy.

B. Being too modest.
Candidates, especially for key technical positions, tend to understate their capabilities. This doesn't mean you should overstate your qualifications; it merely means that you should make the most of what you have. Do not forget that knowledge of how to solve a particular problem can be a strong qualification, even though that knowledge may not have been applied directly in your job experience. Don't let the fear of misrepresenting yourself prevent you from relating the full scope of your experience and knowledge. A little modesty is a good thing, but don't overdo it.

C. Asking too many "Me" questions.
Remember, your objective is to GET THE JOB OFFER. Chances are that most of your questions in this area will be answered either by the personnel department or the interviewers. Don't pursue questions about what the company can do for your during the interview. Emphasize your ability to contribute to the company's goals. There will be a time to ask "me" questions after you get the offer – not during the interview. If you leave the impression that salary and related perks are your number one goal, be prepared to accept the inevitable consequence of having the offer go elsewhere.

D. Failure to "sell" your abilities throughout the interview sequence.
There is no such thing as a token interview. It may be true that some people you interview have no power to hire you, but they certainly have the power to keep you from getting the offer. You should treat every interviewer as the person responsible for you getting the job. Do not treat anyone you meet as unimportant. Do no even allow yourself to think an interviewer to be less important than others. Never depend on someone else to sell your abilities to others. Make the strong and positive pitch yourself.

Preparing for the Interview
What are Employers Really Looking For in the Job Interview?
Common Interviewing Mistakes
Typical Tough Questions
The Anatomy Of The Interview
Post Interview Tips