To calculate the overall star rating and percentage breakdown by star, we don’t use a simple average. Instead, our system considers things like how recent a review is and if the reviewer bought the item on Amazon. It also analyses reviews to verify trustworthiness.
This book doesn't really have step by step guides for newbie artists such as myself. Think of this book as more of a reference guide. With that being said, it is a good reference as it goes into detail about every single aspect of an anime character.