I would like to recommend the book Experiencing Revival by Charles Finney. This is the first book that I read on prayer when the Lord started to teach me about prayer. I realized from Psalm 66:18 that I needed to confess all my sins to the Lord. However, this seemed like an impossible task. How was I to find out what all the sins were? It would take a long time to read the Bible through. One day when I was in the Christian Bookstore looking for books on prayer, I ran across this book and felt compelled to open it. It contained a copy of a sin list. This helped me tremendously in the beginning as I was learning how to pray prayers which God would hear. Not only does sin hinder our prayers, but it also hinders the work of the Holy Spirit.
According to Charles Finney, “You will never have access to the full power of the Holy Spirit dwelling within you unless you completely confess your sins…Unless you are right with God and filled with the Spirit, your work will be mechanical and fruitless” (pp. 39-40).
Finney, Charles. Experiencing Revival. Whitaker House, 1984.