[kqr]

People always look at me funny for recommending it but How To Talk so Kids Will Listen and Listen so Kids Will Talk can be a big help for dealing with adults too. The main difference between a child and a grown-up in terms of how you talk to them is that the grown-up has a larger vocabulary, so you need to resort to tricks like "draw me how you feel" less often.

Although written with another purpose in mind, Never Split the Difference also emphasises over and over how to acknowledge what people are feeling without adding judgment.

[letharion]

I want to second this. All the answers to the OP that pop into my head can be learned from the How to talk so kids will listen series.