Don't let your characters fall flat! Making 2-dimensional characters 3-dimensional.
Characterization is one of those bugaboos of writing that is especially easy to overlook on a comics project where the majority of time and effort is usually spent designing visual elements. In prose, it's hard to sell a reader on a poorly developed character. By its very nature, prose takes us into the mind of a character very quickly. In comics, it's far easier to end up with a character who is all visual flash, and not even realize it until the project has hit the shelves. How many mangas have you read featuring the adventures of a quietly sweet, inoffensive girl, with such varied interests as snacking and being nice to freshmen? Or American comics about tough, brooding anti-heros? Stop me if you've heard the one about the Silent But Deadly Warrior Woman with a Tragic Past(TM) and a penchant for wandering around her apartment in Victoria's Secret undergarments.