You know it's going to come up in every interview, but the question of why you left your previous job isn't at all a deal breaker, unless you make it one. People leave their jobs every day, and your interviewer realizes this. The way in which you answer the question is typically more important than your reason for leaving a past position.
Answer honestly. One of the fastest ways to blacklist yourself from a job, and likely an entire employer, is to lie about why you left your previous company. One phone call to your old boss can turn up the truth, so honesty is the best policy when your interviewer pops the question.
Add some tact to your honesty. You can maintain an honest answer without being brutally honest about it. Suppose you were fired for poor results. Instead of saying that and creating an immediate negative impression in the eyes of the interviewer, say your skills in your previous position did not mesh with the company's expectations. If you were dismissed from your previous job, recruiting company Rakia Galt suggests focusing on your strengths. One of the best and most concise ways of doing that is explaining how the position you're interviewing for suits you and your skills.
Maintain a positive attitude. People become disgruntled with their jobs every day, but listing that as a reason why you left your previous employer will not endear you to the interviewer. He might wonder if you're hard to work with or that you will trash the company should you leave in the future. Always take the higher road. Suppose you hated the way your boss overrode your decisions. Instead of saying that, say that you two disagreed on how best to achieve success.
Keep it concise. When your interview ends, you want to leave the interviewer with memories of your strengths and an impression that you're the best candidate. You don't want him thinking about why you left your previous job. Keep your answer to about two to three sentences.
Prepare to answer a follow-up question. Although during an interview you want to keep the reason for leaving your previous position short and sweet, the interviewer might want more clarification. He might ask a question such as, "What makes you believe this position better fits you?" Again, be honest, and use all that research you gathered about the position and company to your advantage. For example, suppose this position focuses on face-to-face sales and your previous position focused on phone sales. You could say you feel much more at home talking to people and closing sales in person than on the phone.
Remember to remain calm and collected. The subject might be touchy, especially if you were fired from your last job, but act confident. Have an idea of your answer before the interview starts. You don't need an exact script in your head, but a rough outline can prevent stuttering and long pauses.