Started working my way though the classic "How to Win Friends and Influence People" with my 10-yo. I should have re-read this years ago!

It's a classic for a reason. All self-help books have to spend 50% of their time convincing you it's worth reading, and the remainder is the actual content. This is why the title is so off-putting to many, BUT the book itself is a gentle admonition on the requirements for nuanced empathy in human interaction, with a very reasoned approach.