Aparo was primarily self-trained as an artist. His style was primarily in the tradition of his influential contemporary Neal Adams, striving for realistic renditions of his subject rather than caricature or exaggeration. Aparo's muscular figures tended to be leaner than those drawn by most of his peers. He paid particular attention to detail in rendering vehicles, "street clothes", architecture, and landscape. He frequently tilted the viewpoint so that the horizon line in a panel was significantly angled away from level, and used props such as potted plants and furniture to emphasize depth in a setting. He was also known for inserting drawings of celebrities (such as Humphrey Bogart, Peter Falk, Ed McMahon, and Fred Allen) as background characters in heavily-populated scenes.