This book is a useful adjunct toGames People Play: The Psychology of Human Relationships
It is easy to understand and is full of exercises to reinforce the concept of TA, as well as helpful for personal development and self-understanding. there are lots of useful examples to clarify the text. If you are looking for answers to why your life operates in a certain way, then this is a good starting point. There other psychological approaches but you will soon know if TA fits your framework with this book.