***Manners!! *** Etiquette is the secret sauce. Everyone appreciates being treated with respect. Etiquette is the art and science of respecting others. It’s timeless and universal. Customs change, hence the need for constant study, but respect is always the foundation. In summary: Be nice. Start with yourself. Study etiquette. It will help you in every single interaction you have, social, professional, financial, everything. Manners apply to every human, in every interaction, even on the hard days. Hence, the need for practice.
Consider the source. Consider whose company they are in. You may not know much about issue xyz but look and see who endorses them. If people you trust place trust in them.
People want to be heard. Listen to your clients, even when they're upset. Don't make excuses or anything, just let them talk. They mostly just want to be heard. Once they're calm, you can solve the problem.
Go easy on the cologne, perfume, scented lotions, etc. People shouldn't be able to smell your perfume a mile away, only up close. Also, it's generally not appropriate for work.
One regret I have is how sure I was that I was in the right. Looking back I can see now that there were plenty of times when I was the a-hole. I wish I had been able to be circumspect.
Fact: when you drink to excess you are significantly more likely to cause harm to someone or be harmed yourself. Being drunk means surrendering your ability to keep yourself and others safe.