First, you should prepare an answer in advance. It's hard to give a well-thought-out answer if you don't prepare before your interview. Write a list of all the important projects you've worked on in your career. Then, note what the goal was of each project and what part you played in bringing each project across the finish line. Lastly, note the outcomes of all the projects. Make sure you pick a project that was successful (unless you want to talk about an unsuccessful project that you turned around and made a success).

"I worked on several complex projects early in my career. When starting a project like this, I make sure that I understand the goals and then create a plan with various milestones. I also deal with the most challenging parts of the projects early on. That way, if there are any significant issues, I'll still have a fair amount of time to complete the project before the deadline. I also break down large tasks into smaller tasks, so it's easier to understand and delegate if necessary. Detailed planning is important to ensure an important project goes smoothly. For example, last year I was in charge of . . . .(describe an example here)"