This is a great primer on the proper use of dialogue tags. I cringe when I read some of my early writing and see the incorrect dialogue punctuation.
Graeme makes a good point about the overuse of tags, but I would caution that the underuse can make dialogue difficult to follow as well. If two characters are having a lengthy discussion, it needs to be broken up somehow, whether through the use of dialogue tags or attributing some action to the character doing the speaking, as Graeme has illustrated. I can't tell you how many times I have read conversational exchanges and gotten lost in the dialogue because there's a half a page or even more of only talking. And please don't let us know who's talking by having the characters say each other's name all the time. I don't know about you, but unless I'm greeting someone, I don't tend to use their name in conversation all that much.
For example:
"How are you today, George?"
"I'm fine, Joe. How are you?"
"Doing great, George. I started a new job last week."
"Congrats, Joe! I'm happy for you!"
Thanks for a great blog, Renee and Graeme. I'm going to bookmark this.