Of all of the job interview tips I could provide, the most important is to be specific and give plenty of details and examples when you are answering questions.
I had about 2000 clients attend my job search workshops, and I watched each client do practice interviews in every workshop. As a result of watching so many people in an interview situation, I can easily say that the most common mistake people make lies in being too brief.
You may read advice from other sources that tell you to keep your answers brief and to the point. While interviewers don't want to hear long, unfocused, rambling answers, I suspect that the people who give the advice "be brief" have not actually heard many people interview for jobs.
Occasionally people provide answers that are far too long. From time to time I would ask a client to make his or her answers shorter or more focused, but it was very rare.
More often, people provide answers that are far too short to allow the employer to assess the candidate's suitability for the job. Every week, I would tell clients to say more, provide more detail, give examples. Remember, employers invite you to interviews because they want to get to know you. They want to hear specific details about your work related skills and experience, and they want to hear your talk about the strengths you can bring to the company.
As an interviewer, it can become frustrating when someone consistently provides very short, incomplete answers. Interviewers may try to ask follow up questions to get more detail in that situation, but if the interviewee continues to provide very short answers that don't allow the interviewer to assess his or her suitability for the job, at some point the interviewer will likely just give up and end the meeting.
While few people make the mistake of saying too much, if you are ever concerned that you are saying too much in an interview, you can always ask the employer if he or she would like to hear more.
For example, if you know you could add more detail to an answer, but you are not certain whether the employer would like to hear those details, you can simply ask, "Would you like to hear more on that topic?" or "Would you like me to provide a specific example of that?". The employer will appreciate you checking in and will let you know if you should provide more details.
When you are preparing for a job interview, be sure to think about specific details and examples that highlight the skills and experience you can bring to the job. You will make a much better impression on employers when you can provide the kind of details they need to see that you are a good fit for the job.