I love writing dialogue. I like reading it too. That's probably why, no matter how hard I try and how much I really want to, I just can't get through some of those classics. If you know what I mean. My dad was one time flipping through a manuscript of mine and jokingly asked, "is this a novel or a screenplay?"
I also remember back in sixth grade getting an assignment to write a myth. My myth ended up being nine pages long and I couldn't begin to understand why everyone else was turning in two, maybe three, paged papers. Then I realized everyone else had just summarized their story while I had actually written a complete short story. With a beginning, middle, an end and a whole ton of dialogue. My teacher was amazed by how well I'd written my dialogue, too, getting nearly all the punctuation right, even.
When she handed my paper back with a somewhat awed look, she asked, "how did you learn how to write dialogue like that?"
Apparently your average sixth grader doesn't now all the logistics, yet. I shrugged. "I don't know. I guess I just read a lot and picked it up."
That's pretty much how I learned everything when it comes to writing, actually.
Anyway, here are some quick dialogue rules:
When the character "said" "asked" or whatever, use commas. And don't forget to leave the next part lower case. If the character is "in action" or anything else, put a period before continuing. Example:
"Come on," she said.
He shook his head. "I can't."
Use only the simplest tags like "said" and "asked" as much as possible. Don't use them every time someone speaks, though. They can kind of get in the way of the flow. Let the reader imagine what is going on when it comes to the inflection of the voice. But don't leave them completely in the dark. One trick I learned at the LDStorymakers Conference was to use a tag about every three exchanges.
Watch for "floating heads", though. I have this problem a lot because I get so caught up in the dialogue. This can be remedied by putting in a little something about the setting or an action made by the characters. Example:
"I can't see you again." Sally sniffed.
Fred watched a couple walking a corgi across the duck pond for a moment. "If that's really how you feel..."
Alright, there's my two cents about dialogue. Now get out there and write something amazing!