I have been a professional writer for over 30 years. As long as I can remember... even back to my chalkboard-dusted elementary school days, I have concocted stories. Being a writer for hire works for me because I love playing with words, learning about a myriad of subjects, and interviewing people.
As someone who writes for a variety of formats - from print articles and online training to documentary film scripts - I have studied interview techniques. If you're interested in telling nonfiction stories, in whatever format, here are a few tips that I think can help you.
Research your topic before the interview. You need to go into the interview with at least a basic understanding of who you will be talking to, and what you need to learn from them.
Create a list of open-ended questions to bring with you. Even though this will not be an exhaustive outline of everything you can possibly discuss, it will help you maintain a framework for the interview. While I prefer not to share specific questions with an interview subject prior to the interview (I don't want them to rehearse answers that then sound stilted), I will often give them bullet points that are a bit more general. This helps them prepare and feel more comfortable without memorizing specific answers. But if they are seriously anxious and want the questions, I will send them in advance.
Spend time creating a rapport with the person you're talking to. Ask them how their day is going - and listen to their response. They need to know from word one that you are interested in them and their story, and you are a person they can trust. To that end, I also like to explain what I am going to do with the information they share with me, and give them a rough idea of when the project will be complete. One of my clients likes our interview subjects to have a chance to review the piece before it is finalized. I like this because these people know that they will have a chance to correct any points that I may have misunderstood, or that they made a mistake in relaying. Oh, and offer them a glass or bottle of water that they can keep on hand during the interview. Sometimes people's throats get dry when chatting, and other times, taking a sip of water gives them a moment to collect their thoughts and/or composure.
After you've made your interview subject comfortable, you can begin going through your list of questions. I like to start with some simple, innocuous items first, like having them say and spell their name, state their job title (if it's germane to the article), what their favorite hobby is, etc. Once we start on the meatier questions, don't be afraid to pause for several seconds after they complete an answer. You don't want to rush them. Sometimes I have gotten great content from leaving space for them to continue. And don't be afraid to ask follow up questions. Sometimes, if you allow this interaction to be a conversation, you will find unexpected information in those unscripted questions and answers. After we've gone through my list of questions, I always ask if there's anything else they'd like to talk about or anything they'd like to go back to.
After the interview is finished, thank the interview subject for their time, and for being willing to share their story with you. I also like to follow up with a thank you email or text reminding them of when and where the finished piece will be available.
I hope you'll have great success in gathering personal stories for use in your writing. If you use some of these tips and techniques, I'd love to hear how they worked for you - or didn't.