Hey, very good question and thanks for raising. Here's my coaching:
1. Stick to STAR approach, set the context of your story correctly and provide very specific/quantifiable details throughout. Some opening sentences could be: "David, thanks for asking. A few examples come to my mind, but there is one in particular I would like to share..." or "Thanks for asking, I am no stranger to being in difficult situations and have learnt & devised an approach of my own to handle them better...."
2. Always reflect on what you learnt from your situation and how it made yours and others life better. Its also perfectly fine to share a story where you "failed/failing" but came out stronger. Show "fail fast, learn quickly" attitude if need be
3. Link the story to the firms values. Its okay even if you link your story to one value (lets say leadership or integrity or client focus)
4. Dont bullshit, keep it concise
5. Its okay to keep certain details confidential/anonymous. So work with that and don't feel pressured to share every single detail/timelines/names etc