On Writing Well: The Classic Guide to Writing Nonfiction

Zinsser's book is the most widely read and widely used manual on writing non-fiction in English. The argument is adjacent to Strunk and White's (simplicity, clarity, honesty) but expanded to the specific problems non-fiction writers face: interviews, memoir, business and technical writing, writing about places and people. For product direction it is essential — most product documents are badly written non-fiction, and Zinsser's advice is the fastest path to making them less bad. Read it, keep it on the shelf, reread it after catching yourself writing a bad sentence. The only book about writing most product directors need.