The three truths:

Listen

Speak from your customers’ side of the table. It is about them.

Feel their needs and pains. There is no other way to truly understand. Show you understand. You can only help if you understand.

Don’t go on and on about you.

We have one mouth, and two ears. This should be the baseline ratio of the number of “about you” vs “about them” messages across all your communications.
“More about them” is good. “More about you” needs careful justification.

Really get to know your customers.

Do you know what drives them?

Identify commonalities between you and them. You want to be on their side, and get their side, where at all possible.

Mirror their language, tone and look; genuinely.

Acknowledge all input and feedback

Both the positive and not so positive ones.

Your ego is less important than listening.

Respond to feedback; even if this means telling them you disagree or will not be doing anything in response to their feedback.

Just because you hear and understand their point of view does not mean you agree with it. If you disagree, acknowledge their input anyway; then say why you disagree.

Empathy is a useful and difficult skill to learn.
If you make a mistake, acknowledge that and take steps to fix it.

Beware the use of spin and padded truths.

There is a reason why “PR” is often seen as a bad thing to do.

Always do what you promise to. Talk is easy. Many talk well but can’t do.

Get very clear about your intention behind each communication.