By Orson Scott Card
This is one of the first craft books I ever read, and I still revisit it. Card offers practical, straightforward advice on how authors can select the right viewpoint for their story and master character development. Highly recommended for beginning writers who are just learning the ropes, and intermediate writers needing to brush up on their skills.
Another great book by Card is How to Write Science Fiction and Fantasy—if you're writing in those genres, I suggest you pick that up, too.