1. Remember dialogue is action and reaction. When your characters are talking to each other, what one say should bring a response from the one being spoken to. Means what they each says shows some kind of action and calls for a reaction. This doesn't necessarily mean a quarrel. Think of a heroine speaking to her best friend about choosing a dress to wear to an event. What she says triggers her friend's response. What if she's speaking to a non-friend. The answers would be different. Or speaking to her mother.
During the scene, there has to be movement as in body language, tone of voice. Without these, the words become flat. Does she scream, mumble the words. Are the responses emphatic or weak? If there's no interaction and no movement look at the passage again.
We'll be looking at more ways to enhance dialogue while revising in the next few posts.