Well the vampire is usually well done and can be a white shirt opened all the way down, black skin tight jeans, boots, and fangs. A lot can be said depending on how modest and rich your characters are. Face it they can rent a Roman Soldier outfit or go in an old high school sports uniform. Shy guys can always go in something skin tight that doesn't show skin but reveals all. The cowboy in a cowboy hat, jeans, and cowboy boots with a large belt buckle to show off his crotch. Or go sci fi where it is mostly body paint and a very skimpy outfit and claim to be an alien.