Albus Dumbledore lived with perfect etiquette. Having learned early in life what his weaknesses were, he maintained humility in every interaction and worked to always see himself as no better and no worse than those around him. Living with such humility allowed him to exercise self-control when others acted poorly. Albus knew he could not force poor behavior to change. He instead chose to empower those who behaved well.
Another form this etiquette took was in what Professor Dumbledore said. He was often reserved in speaking to others and avoided speaking without having some understanding of the truth. Such reservation, though often a quiet act, encouraged those who knew him to listen to what he did say. By constantly striving to speak truth (or keeping quiet) Albus showed great etiquette.
Many people see etiquette as stiff behavior and formal speech; it can be a way to hide from discomfort or avoid others. Albus Dumbledore did not act this way; rather he acted with consideration for others, humility about himself, and a focus on truth and love. This is true etiquette. The professor had the power to control those around him, punish those that offended him, and create a reality as he desired. He didn’t do any of these things, choosing instead to be restrained and respectful.
A solemn demeanor and perfect speech is not etiquette. Instead, choose your actions carefully, speak truth, and show respect for yourself and others. Doing so allows anyone to follow Dumbledore’s example.