If you've ever dabbled in the wedding industry, you know that the client has the most clairvoyant concerns after the fact. The same is true for other clients. Your job, as the filmmaker, is to coax those ideas out in the pre-production phase. And keep documentation of your plans so if you run into disagreement later, you have something to refer back to.
You can also multiply your efforts if you work together, which is tricky because they'll tell you they'd prefer to stand on the sidelines and let you do your thing. Small businesses are especially guilty of this. You'll have to convince them to do a little prep before the shoot. Have them bring in a friend or family member to model for you. Ask them to think of some projects they can show you.
Clients might be hesitant to open up to collaboration. After all, they're paying you to do a job. They expect you to come and go like a plumber. I like to tell them I'm like the piano teacher. If they don't put in the time to prepare, I can't guarantee results.
My reel, as humble as it is, would be impossible without the help of my clients. When you get them on board with the collaborative process, they might ask to reschedule. That's okay. It means they're starting to take your services seriously and they want to make the best of an opportunity to work with you.