Do not be condescending
Marilynne Robinson on thinking highly of her reader:
My main concern is to be respectful always of my reader’s intelligence. I tell my students always to assume the reader is a better person than he or she is. I tend to assume that good prose simply is accessible, and that condescending to the reader obscures meaning.
Same principle applies in medical communication. Be condescending to the patient, and you lose his trust.