I use scenes to outline the development of each chapter. I also focus a chapter on a scene or scenes. I unimaginatively write in chapters and aim for 20 pages or about 5000 to 6000 words per chapter. This may not be the best way to write a novel, but it works for me. I don't necessarily recommend using my technique of using a chapter length as a goal, but I do recommend using scenes as the center point and outline of the chapter.
Now here is how you focus your writing in scenes. First, you must develop a theme for your novel. I've written about themes before, and I will eventually get to it here one day. Suffice to say, the theme must be somewhat universal, and it must not be trivial. It doesn't have to be to save the world, but it should speak broadly and powerfully. Once you have a theme (it should be written or in some way cohesive in your mind), you can move to the next step.
Second, imagine the actions of your characters. Imagine generally the exciting and interesting scenes that will paint them and your novel within the theme. This is where you begin to design the plot and the storyline. I have been using the terms plot and storyline separately but together since the beginning because, to me, these are two very separate things. The plot is the pattern of events that make up the larger narrative, specifically it is the scenes put together cohesively to make the story that supports the theme. The storyline is the entertaining line of events that make up the narrative. Whoa, what's the difference. The difference, in my mind is the theme. I never want the theme to get in the way of the story. This preoccupation with the storyline prevents this problem for me. I first of all want my writing to be entertaining. I don't intend to beat the reader with the theme, I want the theme to come out naturally as part of the plot as directed by the storyline. My example is Shakespeare. You know each of the plays has an underlying theme, the purpose of the play, overall, is to bring out this theme, but the author doesn't beat the theme over your head. The first purpose of the plays is to entertain. A reader who reads your work and is entertained will get the theme. The reader who is not entertained will put down your work and walk away. No read, no get the theme. Your readers have to first read and enjoy your work.
Third, start to figure out how to get the action of each scene down on paper. To keep this from being overwhelming, outline by scene with a general goal toward some resolution. If you have a general resolution in mind, the novel will grow toward that resolution. Usually, your theme supports this resolution. For example, without giving everything away, I knew Dana-ana would be a novel of discovery. Dana-ana has a great and horrible secret that she is prevented from sharing. She doesn't want to share it because it is so horrible. Because of her secret, groups seek to punish her and demand her death. The resolution is when she must face this horrible secret. Now, she confronts her secret at multiple levels: personally (with Byron and his family), individually (with herself), legally (she was punished for her actions), physically (others want her life because of her secret), and mentally (I don't tell you, you see the effects on her). The novel drives to the conclusion that brings all these together. This may sound very difficult. It is if you try to go at it as a whole. Don't. I wrote each scene as an entertaining piece that drove toward the conclusion. The scenes each had their input, event, and output. These all pointed toward the conclusion. Let me give you an example of this scene outlining. First scene, input Dana stole lunches, event the fight, output Dana knocked out. Second scene, input Dana knocked out, event Byron gets help for Dana, output Byron escorts Dana to her home. Third scene, input Byron escorts Dana to her home, event Dana washes Byron's feet and speaks for the first time, output Byron leaves Dana's house--end of chapter. First chapter ends cleanly and I need a new input for the first scene of the next chapter. Second chapter first scene input is Byron notices Dana in homeroom and speaks to her... The scenes continue from there. In every case, I try to provide an entertaining episode that drives the overall plot and theme. The scenes are the storyline. Tomorrow, I'll see if I can give you more on developing scenes.