Same here, we have a very simple little form that we use for all enquiries. Top line: Name, next: Address, then: Phone number, then Regular or one off, then: How did you hear about us? and finally: Other (any other relevant information). The form is A6, about 6" x 4" clipped together in a pad with a bulldog grip.
It prompts us to ask the right questions and we fill it in as we talk.
All necessary information gathered in a few moments, then I can phone or follow up when I want to.