Why We Pray by William Philip
The purpose of this book is best summed up by the quote it gives from John Bunyan:
Prayer is a sincere, sensible, affectionate puring out of the heart or soul to God, through Christ, in the strength and assistance of the Holy Spirit, for such things as God has promised, or according to His Word, for the good of the church, with submission in faith to the will of God.
Unlike the previous book I read about prayer, this was very useful; I found William Philip was able to identify with his audience easily, with the analogies he uses, and he raised some points that I had never thought of. For example, the book states that if you think that you're not good enough to pray, then you're in effect being blasphemous because you think Jesus dying on the cross wasn't good enough for you.
This felt like a good practical guide to how to pray, such as avoiding having a view of it as "supplementary", which is probably a danger for many people. I liked how the book descibed prayer as an audible form of faith.
This is a relatively easy book to read, and never feels overly preachy, so I would definitely recommend it to others.