Start with the history of comic books. Students who aren't fans of the genre likely are unfamiliar with its past. Discuss the advent of the popularity of modern comic books with the golden age of DC's "Adventure Comics" and "Detective Comics."
Introduce students to some of the writers who have been important in the comic industry. In addition to important figures like Stan Lee from the earlier age of comics, focus on those renowned for the quality of their writing. Have students study the greats like Alan Moore, Neil Gaiman and Frank Miller.
Point out some of the instances where comics and graphic novels have become more accepted as mainstream literature. Talk about the prize-winning issue of Neil Gaiman's "The Sandman" as a good example of the changes in the genre fiction world that began to legitimize the graphic form as literature.
Talk about the reflection of American society through comic books. Use Superman or Captain America as a clear example and show students how the portrayal of America through comic books shifted as the country evolved. Use examples like the pro-war comics of the 1940s and the "Death of Captain America" storyline in the mid-2000s.
Assign students to study and read a graphic novel in the same fashion you assign novels or other prose. This helps legitimize the comic books in the eyes of the students and makes them treat the material seriously. "Sin City," "The Sandman," "Watchmen," "Y The Last Man" or "V for Vendetta" all make for good first reads.