the simpler approach

Besides the Iyengar's book I also have the Swami Vishnu-devananda's book "The Completed Book of Yoga" which was considered as the Bible of yoga when first published. It has only few pages dedicated to pranayama. I followed his very compact explanations and started to do exersises which immediately brought the positive effect. While Iyengar's basic course is preliminary and teaches mainly to observe ( yet it takes a lot of time) Vishnu-devanada gives straitforwardly the core alternate breathing technique which he divided into three steps.