Think about what your story is about.
Have a good idea of the information you need to tell your story.
Create your questions, decide which you will ask, and write them down.
MHTV's Joan says the most important part of interviewing is listening...
Make sure you hear every answer!
Sometimes the answer will change your next question.
Never forget the who/what/where which is essential for news reporting, but a great story always has unique elements that make the reader/listener/viewer feel "connected" to the story.
"A good Reuters story gets straight to the point and has all the main elements – including context, background, human interest, color and descriptive woven in from the top, not just tagged on as an after-thought." -- Reuters
These are a few examples of questions that might get the answers you'll need:
How do you see ___ changing/building/growing?
What are your dreams for _____?
Why do you love ___so much?