I do highly recommend Knitting Pattern Essentials - Adapting and Drafting Knitting Patterns for Great Knitwear by Sally Melville. The book is very detailed, has a wonderful step-by-step format and is structured for every knitter of every skill set. The is wonderful diagramming and photography throughout the book as well as an excellent focus in her "Preparing to Draft" chapter on measuring to make the garment fit your body properly and look best on you - tips that I'll carry over to my clothes shopping to find more flattering cuts and styles in my store bought clothing.
No, I wasn't paid or compensated in any way for telling you about this book. I simply share what I love in hopes you'll love it too.