1 • Stay out of the story’s plot.
Readers read a book to experience the plot in all its magnificence, told with all the skill that the storyteller can manifest. Regurgitating the plot in the sales copy will do nothing but wipe the wonder from it. It certainly won’t sell the story. There are better ways.
How do you know you are down in the plot? Your copy will have a lot of what boils down to “and then this happened.”
If you see a lot of “and then this happened,” you’ve done it wrong. Delete and start over.
. . . .
2 • Use active verbs; avoid the passive tense like the plague.
That means avoiding verb constructions that require “is,” was,” “had,” “have,” and the like.
I’m lucky enough to possess a knack for avoiding passive verbs when I write sales copy. Occasionally an “is” sneaks by me, but that’s rare. However, most fiction writers, when they start writing sales copy, fall into either the trap of focusing on the plot of their stories, or the trap of using passive verbs, or both.
More about this very difficult task at J.M. Net-Grimm.