Dialogue is the primary and most important component in playwriting. The principal purpose of dialogue is to advance the action of the play. Though dialogue sounds like natural conversation, every word of dialogue you write for a character — whether it reveals his aspirations, frustrations, motivations, or intentions — should be crafted to help him achieve his objective.
Here are some of the do’s and don’ts of dialogue:
Use the “rule of three” for important info. If the audience needs to know and remember some bit of information in order to understand what’s going on, repeat that information three times in different ways to cement it in the minds of audiences.
Characters shouldn’t, you know, talk perfectly. In life, people don’t speak perfect English when they converse. Listen to how people speak and try to recreate realistic-sounding speech patterns, flaws and all.
Avoid using clichés in dialogue. Not to “beat a dead horse,” but clichés make dialogue sound dull and uninspired.
Don’t overuse character names in dialogue. People don’t address each other by name in every sentence they speak, because it sounds silly. (Mary, you look great. Thank you, Tom. Do you want watch a movie, Mary? Yes, Tom.) Use character names in dialogue early and then sparingly.
The beginning of a line shouldn’t echo the end of the prior line. The dialogue of one character need not repeat what was said by the other.
Avoid dialogue that’s really speechifying. Avoid having characters speak lines and lines of dialogue without interruption. In life, people usually alternate sentences in conversation, even cutting in on each other. Try to capture the rhythm of real speech.
Keep your agenda out of the dialogue. Let the theme of your play be conveyed by events, not dialogue. If you have to tell the audience what the point of your play is, then the play probably isn’t working as well as it should.
Avoid phonetically spelling out accents and dialects. Just spell the words normally and make sure you cast an actor who can speak with a Spanish accent, for example.