Determine the genre, or category, the reading material is part of. Is it verse, as is the case with Milton's "Paradise Lost?" Is it a play, such as Shakespeare's "A Midsummer Night's Dream"? A textbook or nonfiction work is quite different than a literary classic or a children's book, and will be read differently.
Read all poetry and verse aloud, following the meter whenever possible. Iambic pentameter is the most common meter for English verse but by no means the only one. Poetry simply cannot be read silently and have the same effect on the reader. Poetry is best read for an audience, but even if hyou are reading poetry alone, speak it aloud.
Enjoy reading children's books aloud to a young audience. Animate your voice to bring the story alive to the young ones and inspire in them a love of books and stories.
Scan nonfiction reading assignments for classes, take a look at the review questions or related assignment and then reread the material more closely. This type of material is good for silent reading, unless you are an audio-oriented learner and will absorb the material better if you hear it.
Read nonfiction literature aloud or silently to yourself depending on your audience or lack thereof. My mother used to read P.G. Wodehouse stories or other humorous literature aloud to my father, who enjoyed hearing them. My father would often read C.S. Lewis' Narnia series or Laura Ingalls Wilder books aloud to his children at night. However, both also enjoyed reading silently for personal edification and enjoyment.