Why? Don’t know.
Which? Not sure yet.
Who? Don’t know.
How? Well, there’s a lot of ways one can structure questions for maximum impact. You have to know your audience or at least try to guess some things about them, at least knowing their language at the very least and maybe something about their personalities.
Maybe you can figure out what their driving force is: what is their motivation in life. What things are salient or interesting to them and gear your questions around that.
Do they like terse questions with a few words or long questions with lots of detail and information to help in forming a good answer?
Are they playful or serious?
And I guess the answer to which? is HOW.