An effective way to tell the truth is to be true to yourself, however great the pressure to compromise. An example of this in found in education. Teachers are continually bombarded by "drive-by" programs that promise outstanding results. However, many of these programs are little more than gimmicks designed to trick the students into learning. Teachers are expected to inhabit an "avatar" - but the avatar might not fit.
Most students intuitively know when a teacher is working a program with them; if it is true to the teacher's character, then they will accept it. But students can also recognize when a teacher is implementing a program that doesn't fit. Once they see truth is compromised, trust in the teacher erodes.
Mary Woolstonecraft wrote: "Complicated rules to adjust behavior are a weak substitute for simple principles."
Trust is built on principles, not complicated rules. Sometimes the avatar does not fit.