Here's an example that doesn't even have to be read aloud to see the problems. Imagine the characters as seniors at a posh, expensive boarding school:
April saw it was Mike calling. She took a breath, pushed send, and put the phone to her ear.
"Hello, Mike."
"April, I just heard that you are thinking of withdrawing from school. I believe that would be a very bad mistake."
"But I cannot handle the teasing any longer. I have to leave."
**
Okay, pretty terrible. But let's see if I can make it more convincing:
April looked at her phone. It was Mike, calling, no doubt, to convince her to stay. She pushed send and put the phone to her ear.
"Hi, Mike."
"Hi, uh, I think we need to talk, April."
"I'm not going to change my mind."
"Think about it. If you quit school your parents will kill you! Or at least lock you up for the next year. We've only got four months to go until graduation. Besides, you don't want Piper and Maggie to win, do you?"
"But they tease me all the time, just cause I'm not as pretty, or as popular."
"So what? Let them tease. They're just jealous because you have a family that actually cares about you. And you have friends. All they have are sidekicks."
"Friends like you, Mike?"
"Yeah, friends like me."
**
Maybe not the best dialogue ever written, but instead of stiff it has life. And not because it has more detail, but because it sounds like something teenagers would say.
That's all the pearly nuggets I have for now.