Sound Foundations by Adrian Underhill is an absolute must-have. The name says it all.
I seem to be in the minority in that I absolutely love teaching pronunciation, and it's mainly thanks to this book, which has a very holistic approach. Pronunciation is not intellectual and abstract, it's the physical aspect of language, involving the breath, muscles and so on. It's actually very practical and great fun...students and teachers alike seem to fear it, but there is no need to, as this book will show you. It becomes a pleasure to teach and learn once you grasp the essential simplicity of it, and it's very motivating for students as they can enjoy instant results...they, like you, will be excited by how quickly you progress.
Underhill's phonemic chart is definitive - it's so intuitive, being based on mouth shapes and tongue placement. Move along the chart in any direction and you can FEEL the subtle shifts in your mouth. There's a plan in the book for a first lesson with the chart.
In Sound Foundations you make a natural progression from sounds to words to connected speech. It's a book that restores you, the teacher, to your rightful place as a learner with a wealth of discovery activities which you can immediately share with your students, adapted or not as you see fit. The beauty of it is in this humanistic dynamic, which sets you and your students off on a journey of exploration and discovery. Soon they'll be involved in the process of finding their own English voice - not through drills, mimicking and repetition but rather through awareness, experimentation and curiosity.
Highly recommended, then! ;)