A colleague recently returned from being on an interview panel, and expressed surprise about how unprepared the interviewees were to answer questions about things other than their work experience.  For example, the panel asked each interviewee WHY they wanted the job, and got answers such as "I have 5 years experience as a technician and am well qualified."  
 
It is essential to remember that once you get to the interview phase of a job opening, you have already proven you are qualified for the job.  The interview is not just an oral presentation of your resume.  Instead, the interviewer(s) now want to find out how you will get along with the rest of the team, how dedicated of an employee you will be, and how you handle the inevitable stress that comes at some point with any job.
 
In order to try and determine these more qualitative answers, you are almost sure to be asked two questions: what are your strengths, and what are your weaknesses.  How you answer these could very well get you the job; or destroy your chances.  Let's start with weaknesses.  Most people try to answer this question by basically saying they don't have any weaknesses.  A typical answer is "I get so absorbed in my work that I sometimes work past quitting time."  In our society, working extra hours is NOT considered a weakness (I disagree with this, but that's another article...).  Using such a non-weakness means you didn't answer the question, and you may even come across as rather arrogant.  You need to answer this question with a real weakness, and how you are working on it.  For example, dislike of computers, tendency to speak up too often, or too little,  fear of giving presentations, or difficulty working in large groups, are all real weaknesses that people have described to me in workshops.  These are weaknesses that your interviewers can relate to and may even have themselves.  Be honest about your weakness, and then describe how you are working to overcome it (you go to trainings, sit on your hands to avoid speaking too much, or ask for help on computer stuff, for example).
 
Describing your strengths seems like it would be easier, but most people answer this question by listing their acquired skills from their resume. These aren't strengths but merely experience.  Strengths are things like the ability to rally a group, being absolutely relied upon to do what you said you would do, not losing your temper in times of stress, or creative problem solving skills.  Be prepared to talk about what uniquely personal strengths you bring to every job you do.
 
If you are prepared to describe your weaknesses and strengths honestly and from a personal perspective rather than quoting your resume, you will rise above most of the other candidates.