I started reading another by Jeff Gerke, Write Your Novel In a Month, but it sent me down the Myers-Briggs rabbit hole and I never finished it. I did decide he was right that the pop psychology Please Understand Me 2 is like a characterization cheat sheet.

But one of my favorite books about writing is Characters and Viewpoint by Orson Scott Card. His How to Write Science Fiction & Fantasy is good, too, if that's your genre.