Don't Overfeed Your Reader 

 This is a basic fallacy of beginner writers. They know where their story is going, what the characters are going to do and why. But they don't trust the reader to work it out for themselves. Something like this.

Shaun watched her walk out of the bar with the guy in a suit on her arm. He watched them drive away and could hardly hold back the tears. Gritting his teeth he pulled her photo out of his wallet and set it on fire with his lighter. He let it drop to the floor. He would never see her again. She had betrayed him and now she was out of his life forever. They were finished.

Duh. The reader with a 3 figure IQ worked out what was going on by the time Shaun let the burnt photo drop to the floor. Telling the reader that 'He would never see her again etc' is insulting the intelligence of your audience and that only serves to alienate them. Imagine someone giving you advice on how to cross the road.

Ah, take care when you come to the main road, they drive really fast around here. And if you don't see them coming then you might get hit. And then you might end up in hospital and that would really suck. It would hurt and all.

Enough information already! But many writers don't realise this as they can't see the readers' facial expressions to see if they've got the point already. So instead they belabour the point, reminding the reader throughout the book of the important plot points and explaining the important developments rather than letting the story speak for itself.

An excellent example of this was in the screenplay of the truly appalling move A History of Violence where a decent small town store owner turns out to be... an ex-gangster from 'back East'. As his old gangster friends turn up, his old violent traits come out and his wife screams at him something along the lines of:

Are you having some kind of schizophrenic reaction here?

You'd have thought most of the audience would have worked that out by the way he'd started shooting everyone in sight but hey, Hollywood never went broke by underestimating the intelligence of their audience.

But unless you want to be a mediocre writer writing for a mediocre audience (and there is a buck in that), trust your reader and make the most of one of the most powerful tools at your disposal: understatement.