In an interview with Kristi Hedges, Andrea Howe suggests one way to get beyond the fear of saying the wrong thing and, instead, build trust:

Getting curious is a great antidote for high self-orientation, as it requires you to get away from yourself and into the other person’s world. If you can find ways to acknowledge what’s going on over there, and ask questions to find out more, this shifts your attention.

For example, if a client comes at you angry or dissatisfied, a typical reaction is fear or anxiety. Instead you could acknowledge that you’re disappointed in the result as well, and ask to hear more about the customer’s experience. Say, “Help me understand.” And be genuine. Set an intention in the moment to get the whole world of the other person.