Undersell :: Failing to emphasize the fact that you have related skills;
discussing experience using negative qualifiers (i.e. "I have a little experience...").

Body Language

It is easy to create a negative impression without even realizing that you are doing it. Are you staring at your feet, or talking to the interviewer's shoulder? Be aware of what your actions say about you.

Lack of Honesty

The slightest stretching of the truth may result in you being screened out.

Negative Attitude

The interview is not an opportunity for you to complain about your current supervisor or co-workers (or even about 'little' things, such as the weather).


Lack of Preparation

You have to know about the organization and the occupation. If you don't, it will appear as though you are not interested in the position.

Lack of Enthusiasm

If you are not excited about the work at the interview, the employer will not assume that your attitude will improve when hired.

Rejection

Keep in mind that rejection is a normal part of every job search. For every position, if 100 people apply, 99 will be rejected.If you are rejected, it does not mean that you are not a good applicant. It simply means that you were not the best applicant for that particular job at that particular time. Don't get discouraged. Rejection happens to everyone and is not a reflection of you.
Consider each new application a new opportunity.