If I ever taught preaching, this would be the set text. Every week. Forever.
In ten short pages David Lotz runs through 13 propositions regarding proclamation as God's Word (Dave K summarizes helpfully here). Then he speaks of the form and content of gospel preaching. Check out this paragraph for instance:
Luther envisions an appropriate “rhetoric of preaching” that can only be labelled “kerygmatic discourse.” Such speech does not narrate historical events, instruct in doctrine, describe outward states of affairs (such as “sin” and “grace”), nor exhort to moral activity. It proclaims, announces, declares that God in Christ loves, forgives, accepts you, me, us; and it invites, even incites, the heart’s acceptance of this gift. Such speech takes the objective reality of “God in Christ” and makes (renders) it present and personal: thereby it creates a new reality in my hearing, “God for me,” which through faith (and thus through the Spirit working through that speech) becomes yet another new reality, “God in me.