Don't apologize!While it may seem very counter intuitive, studies are here to back this upUltimately, the customer wants to know how you're going to ensure they can trust the system ⇒ this is the main thing to focus on
Avoid vague language"tons of stuff", "something went wrong"Showing you have a clear understanding of the problem and a solid ability to communicate what it is will help build trust
Perception is factBeing right doesn't matter, our customers' perception are their facts. This is especially important in the fringes of "expected vs desired" (ex: it's expected to take 3h to score but most likely not desired)
Less is moreHelp customers remember the one thing that members, we no longer live in a world where people can remember more than 1 take-away
Prove you understand when asking for detailsAlways rephrase your understanding of the situation and the question in order to show you've made the effort to comprehend their point of vue and that you are asking for clarification on some detail. Oftentimes this will help the customer realize their are some unknown unknowns
Accept detailed questions but focus on big pictureCustomers love to ask questions about details of an implementation or a setup, this is great and should be addressed. However, tabling these items and offering to follow up in order to refocus the discussion on the big picture will help ensure we maximize leverage of the conversation and move the conversation forward