Sadly, I have nothing excessively profound to add from my own, limited experience in writing. Instead I wanted to pass along the following short list I stumbled across in my search to become a better writer.

I can say with confidence that I will be taking these to heart going forward, and in any revisions of past work that I may or may not be working on ;-)

http://fictionwriting.about.com/od/crafttechnique/tp/dialogu...
Personal thoughts on my own failings after the break. :-)

For my part, 2 ("Not Exactly Like Real Speech) and 5 ("Don't Overdo Dialogue Tags") are probably my biggest problems, along with 6 ("Stereotypes, Profanity and Slang"), to a lesser extent.

Anyway, I just wanted to pass this along since I found it really useful. I'm going to try and keep more of this in mind when I write, but there are no guarantees.

Writing is like pizza. Everybody knows what they like, and good luck getting two people to agree on a shared order. ;-)