It's a matter of trust. That sounds a little heavy but I really want you to trust me to get the shots you want and need. That's why we'll talk about your ideas and I'll ask a bunch of questions. You must be able to trust me to give you photos that will fit your plan just as you wanted.
I find this approach applies to everything from shooting head shots to shooting a conference. Sometimes I feel like my client believes that I know what he or she means without much explanation. I can always benefit from plenty of detailed explanation. I may have heard most of it a hundred times but it's much better that I know just what you expect than to just draw conclusions from my experience.