Don't go into personal struggles that affected your professional life, such as insomnia or partying too late everynight with the crew. Also, don't detail things you had to research that you should've already known to do your job effectively. The less obvious and more innovative the better.

I was in charge of monitoring our order writers' orders. Something was happening with our pet food order. The employee responsible for that order did their best, yet their items were continually out of stock. The order writer was just as confused as everyone else. So I inspected their numbers, and they didn't match up. After further examination, I realised another supervisor who I rarely crossed shifts with was adjusting the order without communicating it or notating their adjustments. I made efforts to coordinate with all parties and the issue was resolved.