Deploy Empathy: A Practical Guide to Interviewing Customers

Hansen's book is a practical manual on customer interviewing written by someone who has done hundreds of them inside a bootstrapped software company. The book's strongest feature is its granularity: transcripts, question phrasings, the actual sentences that open a conversation and the ones that close it. For product direction it is the most hands-on book on user research currently available — less theory than Torres, more concrete than Ulwick. Read it before running your next round of interviews; most PMs will find half their current habits flagged as unhelpful. Short, self-published, usable.