'Tell me about...' type of questions are very popular. It is more effective because it is asking for an answer that comes from experience. If you don't have a particular experience in one of the questions below, make one up. You should prepare ahead of time because you don't want to make up a story during the interview. It will be too hard to sound believable. Finally, you should know that some questions will not be asked to certain job types. For example, if you are not in a management position, you probably won't be asked how you saved the company money. Or if you are not in sales, you won't be asked about making a great sale.
These types of answers are usually long because it is explaining an experience. If you want the interviewer to understand the significance of your story, they will need to understand it. So all my examples will be a little longer than regular interview questions. Finally, a lot of these are my own experiences. I encourage you to think back to your experience and create one. I'm providing my answers so you can see the structure and learn from my answers.
"Tell me about a time you made a mistake."
The best answer for this question involves learning something from a mistake. If you are having difficulty thinking about a mistake you made that will be an effective answer, try to think of a lesson you learned that improved a good trait. Making a mistake is not good, but since you have to tell them something, you should tell them something that makes you look good. For an example, let's create a scenario where you learned how to be someone who anticipates problems.
Short Answer
"I was given a project to complete in a week. I understood the project, but I misinterpreted one section. After completing the project, I was told by my manager that it was done incorrectly. I really made a mistake by assuming incorrectly in one of the sections instead of asking for clarification. I learned not to assume through the mistake I made."
Long Answer
"I had a project I was working on, and while I was in the middle of typing up my documentation, my computer started acting weird. It froze for a while and so I rebooted. After 10 minutes, the computer showed a blue screen saying that there were problems and recommended that I reboot the computer again. After another reboot, everything appeared to be ok. I continued my work and finished for the day. I spent two days on this assignment and when I went to retrieve my data the next day to double check my work, my computer wouldn't start up. A technician came and found that my hard drive malfunctioned. I lost all the data and lost two days of work. I was disappointed and thought I would never trust a computer again, but there was a great lesson to be learned. I had a couple of warnings and I ignored them. From then on, I practiced being someone who can anticipate problems. I now think of potential problems ahead of time and pay attention to details along the way. If I applied this sooner, I would have saved the data on another computer and I wouldn't have lost a couple days of work. But I can't say I regret making the mistake because it made me someone who can anticipate problems better."
This is a minor mistake, and you can say it is really the computer's fault. But this is a good example because I wasn't really at fault. The computer was. But this example is wording it so it looks like the person's fault and it explains how a great lesson was learned. In the end, this candidate became a better person through this mistake. Learning from a mistake is probably the key point here, and this example demonstrates that.