One of the major differences between good writing and bad writing is dialogue. If the characters sound like robots, you can’t get invested in them.
You need to read your dialogue aloud, preferably with a partner, and decide if people would really say these things in a conversation.
Getting dialogue to a point where it sounds like it would come out of a human’s mouth is really rewarding. I’ve gotten a lot of laughs from people reading my work just because of the way my characters phrase or narrate things–it’s like they’re real people that happen to say things (that may or may not be humorous) in a funny way.
Here’s a resource I just recently was linked to, if you’d like some help with making your dialogue sounds like it’s real people talking.
Your characters are living, breathing individuals (most of the time). They will not talk or interact with other characters the same way as someone else. (Caveat: Unless the point is that they do so.) Even if they’re robots, they’ll still be unique (probably).
If you have a royal elf talking to a human peasant, they are going to speak drastically differently (unless there’s something strange in your world that made them similar).
If you aren’t sure if your dialogue is natural, have a pair of friends read it together while you and another person listen. The four of you should be able to reach some kind of consensus on the matter.
Spend some time adding action to your dialogue. Not just “he said as he sat down on the couch.” Try stuff like “‘Blah blah,’ he said, licked his lips self-consciously, and idly stabbed at his macaroni, hoping no one would notice that he didn’t care.” Have your characters stand up when they’re upset or passionate about what they’re saying and sit down when they feel heavy-hearted. Each movement should have a reason behind it. Talk to a friend who’s in theatre about this. They’ll know what I mean.
***If you don’t have any friends in theatre or anyone who’s willing to go over dialogue with you, you can ask me. I don’t mind. In fact, I’d really love to help you. 🙂 So please, please don’t be afraid to ask for my help, advice, information, or anything else!***