We try not to be overly impressed by titles. Avoid courtesy titles (Mr., Mrs., Miss, Ms.), except as business etiquette specifies them in correspondence. (See "Guidelines for Addresses/Titles/Salutations in General Correspondence," available through the Office of the President.)
"Professor" is never abbreviated. The formal title "Doctor" is almost always abbreviated; however, avoid it when its use is not critical to the subject of the text. In programs and similar publications, an academic title (e.g., Ph.D., D.Div.) following the name takes precedence over a "Dr." preceding it (never use both). Physicians, dentists, psychiatrists, etc. may still properly be listed as "Dr." in a first reference, but again, dont use both the formal title and the degree.
"Reverend" or "Rev." is used to denote ordained ministers. It is properly preceded by "the" whether or not abbreviated. However, note that it is an "honorific" title and an adjective, like "the Honorable" (when addressing government officials such as judges, ambassadors, and representatives), and is properly used only with the person’s full name or with a courtesy title and last name—using the word "Reverend" as a noun (as in, "Good morning, Reverend") is an informal usage, with which some clergy take umbrage:
If you expected that this page would discuss titles of books, music, and other works of art, this is the paragraph you'll want to read: Follow the Chicago Manual of Style (7.126154) rather than AP when referencing titles of books, magazines, newspapers, articles in books or magazines, music, works of art, etc. Generally: