What narrative techniques does Dickens use in Oliver Twist?

Oliver Twist is what's known as a progress.  In fact, the subtitle was "A Parish Boy's Progress" originally.  In a progress, the main character does not take action directly.  In short, he does not make things happen, things happen to him.  Oliver does not grow or change as a character, and he does not make choices.  This is an interesting choice for a main character, but consider it historically.  Oliver Twist was the first novel with a child as a main character.  Dickens was interested in A Pilgrim's Progress and wanted to mimick the model.  He was a young writer then, and had never written a full-length novel.  His first published book was The Pickwick Papers, which is really a collection of humorous sketches.

It's important to note that this was Dickens's first attempt at outward social commentary aimed for reform.  He was successful, a fact incredible in itself.  By humanizing Oliver, the Poor Law became an atrocity that eventually England couldn't stomach.