Are there different degrees of "confidentiality"? What is the best way for a psychologist to maintain confidentiality of communications with patients?

A non-tech savvy friend of mine is a psychologist. She has many patients who constantly invite her to communicate through all sorts of mediums such as text, email, voicemail, and other mediums. But she is concerned she is not knowledgeable enough about information security and would like to learn more.

As a doctor (a practicing clinical psychologist), she has two primary goals:

1. To be able to preserve the confidentiality of communications with her patients.


2. To make intelligent choices about how she communicates so that, if information must remain off the record, she knows how to communicate in a way that remains off the record.

Given the problems with information security these days, she doesn't know what the best way is to achieve these goals, so I suggested bringing the question to Information Security SE.

Obviously, my friend isn't likely to want to read lots and lots about information security. She also is looking for information tailored to those two particular goals, which are probably common for all psychologists.

My Question:

What is the best way to achieve the two goals stated above?