The following is an excerpt from my book How To Write A Novel: The Fundamentals of Fiction, Chapter 7:
1) Use Simple Tags Sparingly. Fancy tags like “he expostulated” or “she espoused” are less clear and more distracting than anything. So keep the tags simple when you absolutely must use them. Instead, convey the manner in which a character speaks instead. Make it obvious from what is said.
2) Instead Of Tags, Use Actions. People talk while actively engaging in activities. So should your characters. Giving them business to do during dialogue allows you to identify who’s speaking without resorting to overused tags. Some can come in the form of characterizing the speaker: “His eyebrows lifted with menace,” for example. “Bob’s fist clenched as he spoke.” “Tears rolled down her cheek with every word.”
3) Avoid Expositional Dialogue When Possible. We’ve all violated this rule, but especially when two characters should already know the information being imparted, it seems unnatural and distracting. In such cases, internal monologue is a better tool and more natural. Characters may think about stuff they already know but they wouldn’t tell each other stuff each of them knows.
4) Keep It Short. People talk in choppy sentences. Long soliloquies are rare. So in dialogue, use a combination of short sentences to make it flow and feel like real people talking. Let them interrupt each other, too. People do that in real life. It adds to the pace, tension and drama of it.
5) Avoid Phonetic Spellings For Accents. They are difficult to read. Indications of dialect can be used instead to get the reader to do the rest. Overuse of a dialect becomes distracting to readers and can actually take them out of the story. Keep the words your characters say as unobtrusive as possible so your story flows seamlessly.
6) Dialogue Is Conflict. Conflict keeps the story moving. People talk like they’re playing table tennis-back and forth. This moves the story forward. Lace your dialogue with conflict. It adds dramatic urgency to every line the characters say and keeps the story’s pace.
7) Use Other Characters. Let a character imply who’s speaking to them by saying something specific to only that person. If you use business well (see number 2 above), having a character refer to something the other character is doing is a great way to do this.
8) Give Each Character A Distinctive Voice. Overdo it and its caricature but we all have our own speech tics. Create some for your characters and sprinkle them throughout. Readers will learn them and know who’s speaking. For example, Captain Jack Sparrow loves the term of affection: “love” and uses that a lot. He also says “Savvy?” a great deal as well. He has others you can probably remember, too. Study characterization and see what other writers have done.
9) Speak It Aloud. Talk it out. Get inside the heads of your characters and say the lines. Play out the conversation you’ve written. Does it sound natural? Does it flow? Your ear is often a better judge than your eyes and hearing it will give you an idea how readers will hear it.
10) Remember What Medium You’re Writing For. TV and Film dialogue and novel dialogue are not necessarily the same. There is no third party to use intonation, facial expressions and/or body language to bring it to life. Your words alone are the conduit between yourself and the reader and your prose skills and the readers’ imaginations make it work.
Altogether, remember, the goal of speech tags is solely to help readers keep track of who is speaking, when. That is their sole purpose. It is not a chance to insert adjectives for emotional effect or to show off fancy word slinging vocabularies. They are another tool best used as subtly as possible.
In On Writing, Stephen King writes: “As with all other aspects of fiction, the key to writing good dialogue is honesty…It is important to tell the truth; so much depends on it…The Legion of Decency may not like the word shit, and you might not like it much either, but sometimes you are stuck with it… You must tell the truth if your dialogue is to have resonance and realism…If you substitute ‘Oh sugar!’ for ‘Oh shit!’ because you’re thinking about The Legion of Decency, you are breaking the unspoken contract that exists between writer and reader—your promise to express the truth of how people act and talk through the medium of made-up story.” That some readers may not want to hear the truth is not your problem. Your quest is to tell the truth at all times, to keep their trust, and sometimes the truth is uncomfortable for all of us. Dialogue being how characters talk is one of the most important crafts to writing your novel. It must feel authentic and real for readers to believe your characters could be real people.