"Use dialogue that sounds natural."
Dialogue seems to get lost in translation, especially with new screenwriters. There's this urge to compose lines that are on-the-nose (that is, reveals exactly what's happening in the story) or irrelevant banter that's better left for some coffee shop chit-chat. Whatever your genre, no matter the story, make sure your characters sound authentic!
The purpose of dialogue is not to simply convey a message from one character to another. Instead dialogue is an element of screenwriting that drives the theme forward as well as reveal the core personality of your characters. The spoken words you choose for each character must coincide with their actions on screen.
Dialogue must, must, must - cannot say this enough - must feel genuine. It must flow from your characters' lips, to our ears, and make our heart feel something - empathy or apathy - for each character. One common mistake is to answer a question with a question. For instance, Character A asks, "Can you be ready in five minutes?" Character B responds, "Five minutes?" Nothing in B's response reveals character or speaks to the storyline. Another mistake is to use the names of your characters as a way of introducing them to your audience.
Hi Barry - nice to see you today.
Oh, John - I did not see you there.
That's ok, Barry.
Say, John, have you seen Jennifer?
No, Barry, I have not.
Ick - sounds unnatural and the use of first names LIKE THIS never happens in real life.
How do you know that you've used a tone that will resonate with the audience?
- Read your own script aloud. Sure, others may think you're crazy, so this is better left for a time when you're alone.
- Gather some friends (preferably with acting skills) to do a table read. Nothing like hearing different voices speak your words and discovering how they translate the tone in their heads.
- Use a computer-generated voiceover. This is my least favorite since the only one I've seen so far sounds like a bunch of robots. BUT, this is better than nothing, especially if you can tweak the voices ever so slightly to help differentiate them. Final Draft software includes this option, which I've used.
In summary, the audience needs to be able to deduce the personality of each player in order to understand the dynamics of the relationships. And it needs to feel REAL.