develop characters with prominent characteristics, and decide a unique situation the characters are in. write a plot on how the zombies came into being and how the characters met [or write about them meeting in the novel]. Graphic details usually grab the attention of readers who enjoy gory zombie books, and a good twist makes every book good. Also be sure you state the characteristics of the zombies, so the reader knows what the characters are up against.
oh ok I already conjured what caused the infection i need help with the plot but this should do