The honest difference between a method and a guess is that a method knows how it can fail and checks for it. BNN carries a standing list of prediction errors.
A few of the twelve
Timing an event before confirming the promise exists. Using transit as the main system. Reading houses in isolation, ignoring the trines. Calling a quiet year a failure when no planet is activated. Confusing possibility with event - an interview is not a job, a meeting is not a marriage. Collecting only the evidence that agrees with you. Predicting an exact date far too early. And the cardinal sin: using fear as if it were certainty.
An unexamined prediction is not a prediction. It is a wish with a date on it.
Every reading should end with a confidence score and a validation loop - what would prove this wrong, and did it come true. That willingness to be checked is the whole ethic of this Association: astrology you can audit.