Dialogue that is written correctly, between two characters, can quickly grab a reader's attention and bring them into the story. The number one trick is to make the dialogue sound realistic. Each and every writer has his own unique way for writing dialogue, however, there are some tips you can follow to get you started until your develop your style.
Use your dialogue to define your characters. The number one way to give your characters a personality and a "real" feel, is by using dialogue. Before you begin to write dialogue, make sure you have a clear understand of who your characters are and how their personalities will come through their dialogue.
Pretend your characters are on stage or TV. When you begin to write your dialogue, envision them on TV or in a play. Think as if they are standing right in front of you having a discussion. Make sure that whatever they are saying sounds real and is believable.
Remember the characters' demographics. When your characters are having a discussion, make sure that you bring their age, where they live, and education level into how they would talk or respond. For example, if they are from the south, do some research on how people in the south talk or if they are children, understand how different children would respond.
Pay attention to conversations happening around you. While you are writing your dialogue, pay close attention to people around you and how they have conversations. Make sure that you use everyday language in your characters' conversations. However, be careful with the amount of slang you use. If you want your story to last for years, use language that will last for years.
Add colorful and unique words. Instead of overusing the "he said" or "she replied", try adding variety and personality to the dialogue words. Keep the dialogue exciting and not too long. You don't want your readers to be bored with too much dialogue.
Read your dialogue out loud. When you are finished writing your dialogue, read it out loud to yourself or to another person. Make sure that it flows and makes sense. When you read it out loud you will be able to quickly hear where you need to make changes.