Traps to avoid (when you're writing your mystery)

I'm a member of Sisters in Crime (a great organization that's open to male mystery writers and mystery fans of all genders, too) and today the group's chat invited suspense master James Frey to answer some questions. One of the first was "What are some common mistakes you see among novice writers"? I hope nobody will mind if I print his answer in its entirety, because I thought it was very smart and useful. Here 'tis:

I can give you few common beginner mistakes:

1. The hero is often inert. Other characters may be active, but the hero just sits and watches and thinks.

2. A lack of conflict in the scenes. Often the dialog has a lot of information but not a lot of conflict.

3. The dialog is trite. The lines are what I call "pedestrian." There's no color or metaphor in them.

4. The obstacles in the path of the hero are too easily overcome.

5. There is no mystery in the murder. Okay, there's a mystery as to who did it--there's a body--but there's not really a mystery in the sense that say, there's a bullet wound but no bullet, or the victim was in a glass elevator and was strangled while three thousand people could have seen the killer (but didn't), or a toy doll was found holding the murder weapon with nobody around.

6. There's nothing special about the hero.

Thank you, James!