Be a Witness, Not a Judge
When asked to give feedback or evaluate a project, it is best not to think of yourself as a judge, offering irrefutable sentences, or a prosecutor, trying to build a foolproof argument, or even a defendant, who backs up every statement with graphs and charts.
Instead, think of yourself as a witness, giving a "clear, specific picture" of what you observe.
Speaking as an observant witness rather than playing one of these other roles is challenging at first, but when you have mastered this discipline, you will find listening ears where before you encountered resistance. Thanks to Peter Block for this insight.