The STAR Method
Behavioral based interview questions are best answered using the STAR method.
The STAR method is a structured manner of responding to an interview question by discussing the specific situation, task, action and result of what you are describing in order to validate an answer.
Describe the situation you were in. You must describe a specific event or situation, not a generalized description of what you have done in the past. Be sure to give enough detail for the interviewer to understand. This situation can be from a previous job, from a volunteer experience, or any relevant event.
What goal were you working toward?
Describe the actions you took to address the situation with an appropriate amount of detail and keep the focus on YOU. What specific steps did you take and what was your particular contribution? Be careful that you don't describe what the team or group did when talking about a project, but what you actually did.
Describe the outcome of your actions and don't be shy about taking credit for your behavior. What happened? How did the event end? What did you accomplish? What did you learn? Make sure your answer contains multiple positive results.