In Preaching with Confidence, James Daane gives a good outline of the science of constructing a sermon. He emphasizes that a sermon should have one point. Parishioners of average intelligence should be able to state that one point in one sentence. If they cannot, the minister has not done well. The minister, also, must of course be able to state the one point in the form of a proposition which contains a subject and a predicate.
Besides writing some helpful stuff about the nuts and bolts of a sermon, there is a good chapter entitled: "The Current Status of Preaching." Many Protestant preachers are somewhat embarrassed to be called "preachers." They no longer authoritatively proclaim the word; rather, they want to be known as facilitators and enablers. After reading their text, many no longer say something like: "I proclaim to you the Word of God"; instead, they begin with: "I just want to share with you." This crisis of confidence found in preachers is reflected in the pew where many place more stock in their small bible study groups as a means of faith than the preaching of the Word in the worship service.
An anecdote: After a service a mother told him that as he had entered the pulpit, her toddler son had whispered, "Mommy, there's God!" Mother and Rev. Daane chuckled about that. Upon later reflection he concluded that the toddler had a better understanding of the mystery of preaching than the sophisticated mother and minister (see Luke 10:16).
The book also has some good things to say about "altar calls." The altar call phenomenon suggests that the non-Christian is free either to accept or reject Christ whereas, rather, preaching has attached to it the command to repent and believe. No one, hearing the gospel, is free to reject it. To reject it is a damnable offence. Altar calls enable the sinner to retain a sense of autonomy, the right and might to say No to the gospel. They reinforce the impression that the gospel is optional.
Although many evangelical preachers like to say that preachers must preach for a decision, with the altar call method, the call to decide actually comes after the preaching during the altar call. The altar call, rather than the preaching of the Word, then supposedly becomes the means of grace.