Writing good dialogue is an art unto itself and is arguably more difficult than writing description or narrative action.  For some writers dialogue flows naturally from their fingertips.  But for the rest of us who are not so wonderfully gifted dialogue comes at a price, and only after a great deal of conscious effort and banging our heads against the wall.  To make things a little easier, we have assembled an annotated list of the most important things to remember when writing dialogue in your next screenplay, stageplay or novel.

1. Thou shalt write dialogue with PURPOSE.  Good dialogue either reveals character or advances the plot in every line.  Great dialogue does both.  Dialogue which serves neither purpose has no place in your story at all and should be cut.  Want to see a film with great dialogue?  Watch Casablanca.

2. Thou shalt write dialogue based on character TACTICS.  Why does a character bother to say anything at all?  Because (s)he wants something.  But a character can’t just want something without employing a specific tactic to pursue that desire.  Therefore dialogue is determined by a character employing a tactic to achieve a specific goal.  A tactic is motivated by what the character wants right at that moment and how he is willing to achieve it.  Either the tactic succeeds and a new desire is born or, as is more often the case, the tactic fails and the character must use a new tactic or give up.  Read some tactical dialogue in just about any stageplay script or the popular novel The Hunger Games.

3. Thou shalt write dialogue NATURALLY, NOT ACTUALLY.  That is, write dialogue so that it sounds natural but is not in fact actual conversation.  Dialogue is no more real speech than a movie is real life.  Unlike actual conversation, dialogue is carefully and consciously sculpted to achieve a deliberate purpose.  When writing dialogue, skip or briefly summarize the less useful parts of conversation such as greetings and meaningless exchanges so as to get to the real meat of the conflict as soon as possible.  Avoid hedges and fences which slow the pace of dialogue (such as “Well,” or “Look,” and “You know,” or “, you know” as well as frivolous insertion of character names and other weakening qualifiers.  Even conversational writers like David Mamet in Oleanna still only approximate actual conversation.

4. Thou shalt write dialogue using both TEXT and SUBTEXT.  Dialogue has two parts: the readily visible text on the page (that which is being said) and the hidden subtext(that which is not being said).  Why do you need both?  Because subtext without text is not dialogue while text without subtext is dull (Krull is a great example).  The audience may even feel like something is missing because people seldom say what they mean in real conversation, instead skirting around the issue at heart by means of various tactics.  Use subtext to deepen your story, to convey exposition and to avoid on-the-nose dialogue (saying exactly what is meant).  A good rule of thumb is to never say what you can otherwise imply.

5. Thou shalt write dialogue that is UNIQUE AND APPROPRIATE TO CHARACTER.  Every character should be recognizable by their dialogue without having to read the character names on every line (your brain tends to skip over character names anyway).  The emotions and tactics of the character should be reflected in his or her dialogue as well.  And while a character’s dialogue must be distinct, don’t forget that it must sound natural, so don’t give your character lines that no one would ever say, especially your character.  No one would ever mistake dialogue spoken by the character Sawyer in the TV show Lost for any other character on the show.  Try reading your dialogue out loud to spot awkward lines.  Better yet, get together with a few friends (or actors, or both) to read and talk through trouble spots.

6. Thou shalt write dialogue using COMPRESSION.  Compression means that you pack the most amount of punch into the least amount possible by means of subtext and implication.  To compress your dialogue, hunt down redundant beats and lobotomize them.  Redundant beats are repetitious and will come across to the audience as boring and annoying.  Combine or cut any beat that repeats what another already conveys.  Remember: It is better to write simply than to simply write.  Excellent examples of highly compressed dialogue can be seen on the TV show Lost.

7. Thou shalt NOT write dialogue as a REPLACEMENT.  Dialogue is not a replacement for action, visuals, or character.  At its most basic level, dialogue is essentially telling.  Don’t tell the audience what you can show them.  The infamous sword-and-sandal epic Cleopatra substitutes a final sea battle with dialogue—but only because they ran out of money to film it.

8. Thou shalt write AS LITTLE DIALOGUE AS POSSIBLE.  Dialogue is the primary means of conveying story in a stageplay, while film uses visual storytelling and novels use descriptive narrative.  But just because all three forms use dialogue doesn’t mean you should write dialogue until you can write no more.  Many inexperienced storytellers tend to use dialogue to over-explain elements of character and plot that should have been illustrated some other way.  Bloated dialogue also has a tendency to slow pacing and bore the reader unnecessarily.  As in writing description and revealing plot, only explain the minimum amount required to understand the story in order to draw in your audience.  Never explain everything.  Don’t spell out the obvious things although you may have to shed light on the things that aren’t.  The more you explain to the audience, the more passive and less emotionally connected they become to the story.  The more mental legwork the audience must do to connect implied dots the more emotional attached to your story and characters the audience becomes.  Also avoid bogging down the story with frequent long speeches, monologues or soapboxing (preachiness or unnecessary exposition).

9. Thou shalt write dialogue FREE OF CLICHÉS.  Avoid all clichés like the plague (a cliché in itself).  Clichés stick out like a sore thumb (another cliché) and each instance pulls the audience out of immersion of your story’s world.  And that’s bad for business.  Want to hear clichéd dialogue?  Watch any straight-to-DVD film sequel.  For the opposite, watch Silence of the Lambs and pay careful attention to the uniqueness and density of the lines.
   
10. Thou shalt write dialogue that is APPROPRIATE TO GENRE AND CONTEXT.  Comedy dialogue should be funny but shouldn’t go out of its way to tell a joke—the dialogue still must move the story forward.  Action and Thriller dialogue should be terse, compact and minimal.  Emotional dialogue should be heartfelt and not trite.  Never write dialogue which does not fit the tone of the story, the scene or the character.  TalladegaNights: The Ballad of Ricky Bobby illustrates how story-driven jokes can be both funny and heartfelt.