I just finished reading a great book by Ken Hemphill. It is called The Prayer of Jesus: The Promise and Power of Living in the Lord's Prayer . This book is based on the Lord's Prayer and breaks each line of the prayer down and gets a little deeper into why we should pray like the Lord. At first glance, I wasn't really sure that I wanted to read it, but I kept feeling that all to familiar nudge from the Holy Spirit guiding me to read it. First and foremost, I am glad that I obeyed, and second I received a great blessing in regards to prayer by really getting in and studying this book.
If you are looking for a great book to dive into about prayer, then may I suggest this one? You will be amazed at what you can learn from a simple prayer.