I've compiled this list from how-to-write books that I've read, from boring stories that I've perused, and from complaints my editors frequently said about my own writing.
1. Flat Language
Whether it's description, dialog, action, or internal thoughts, it should be colored with personality. Even if you are writing in third person. This is how you build style.
2. Yes-Men Characters
A book can have 1-dimensional characters and still be good. These are like one line jokes--you can still get a laugh out of your audience. But flat characters are emotionless cardboard cutouts that do nothing but fill the plot. They do exactly as the author wants to move the story. A good book has character-driven plot rather than plot-driven characters.
For example, three characters, chatting together, say:
"We should go in there and steal the book.""Good idea. I'll help you.""And me too!"
When in the real world do three people cooperate together so easily? It reminds me of the song I hate the most in this world. "Shiny Happy People Holding Hands."
Makes me want to blow them all to smithereens.
(FYI, this is the shortcut version of my original writing of Barra planning to get the hidden book from Ashon's office.)
"My eyes sparkled like blue gems." Um, how do you know what your eyes look like, unless your looking in the mirror? Who ever comments on their own eyes? I don't. Well, unless I'm talking to my kids. I want my kids to hear me say good things about myself, just as I say good things to them. But other than that...
Or "The door opened behind me, and Bob walked in." And I have eyes in the back of my head.
And POV rules apply to writing in third person as well. Each scene should be written from one perspective, or the reader will be pulled out of the story. Readers want to experience the story from the minds of the characters. Not from the mind of the author.
I don't want you to tell me about your vacation, show me the pictures, and give me a slide show presentation. I want you to take me with you. I want to live it, experience it, taste it, smell it. I want to be there. Don't we all? That's true story telling.
5. The Prologue.
Don't tell me about your character before we even start the story. Boring. I'd rather jump right in and take off. Lace the details into the action.