I came upon this great article on public prayer by John Newton. It's really good!
Some highlights....
"The prayers of some good men are more like preaching than praying. They rather express the Lord's mind to the people, than the desires of the people to the Lord. Indeed this can hardly be called prayer. It might in another place stand for part of a good sermon, but will afford little help to those who desire to pray with their hearts."
"It is possible to learn to pray mechanically, and by rule; but it is hardly possible to do so with acceptance and benefit to others. When the several parts of invocation, adoration, confession, petition, etc., follow each other in a stated order, the hearer's mind generally goes before the speaker's voice, and we can form a tolerable conjecture what is to come next. On this account we often find that unlettered people who have had little or no help from books, or rather have not been fettered by them, can pray with an unction and savour in an unpremeditated way, while the prayers of persons of much superior abilities, perhaps even of ministers themselves, are, though accurate and regular, so dry and starched, then they afford little either of pleasure or profit to spiritual mind. The spirit of prayer is the fruit and token of the Spirit of adoption."