Let's start with the two most fundamental points as regards dialog tags because if you buy them, everything else flows naturally.
1) Dialog tags should do nothing more than advise the reader who is speaking, in case it's not obvious.
When you watch a conversation between three people, you know who is speaking by sight, sound (tone and a spatial sense of where the voice is coming from) When you eavesdrop (don't lie now, you know you do), you rely on sound. When you read, you rely completely on context. I'll come back to this.
2) Dialog tags distract the reader from the story.
There. I've said it. Plain and simple. Stories are about your characters and what happens to and because of them. Your characters do stuff, see stuff, feel stuff. They don't do, see, or feel dialog tags. Authors do. If you want your readers caring about your characters, keep the focus on the stuff your characters do, see and feel. If you want your readers caring about the author, write an autobiography.
Right, then. Context. Readers need to know who just said those precious pearls of dialog on the page. Dialog tags work, but, IMHO, the best way to convey such a context is to have the character do something prior to speaking. Action beats. You can't always do it, and sometimes it's just silly if you do it for the sake of doing it, but when you can, you should. Check out this tedious bit of dialog.
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"Lovely day, isn't it?" asked Sally.
"Oh," replied Alfred. "Smashing. Truly."
"I wonder if we'll ever see the rains again," said John.
"I highly doubt it," replied Alfred.
"Oh, stop whining already," said Sally.
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Well, there's no doubt you know who is speaking. But this exchange suffers from a case of talking-head-itis. Nobody is doing anything. As far as you know, there's just some dismembered heads on a table babbling. How do I make it better?
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Sally leveled the pistol at Alfred's chin. "Lovely day, isn't it?"
Alfred swallowed hard, casting a sideways glance at the barrel of the gun, while trying to keep the car from barreling off the road. "Oh, smashing. Truly."
In the back seat, John made a few more feeble attempts to free his wrists from the fishing line binding them together. He blew a mop of sweaty hair from his eyes and peered out the window. "I wonder if we'll ever see the rains again."
"I highly doubt it," replied Alfred.
Sally shook her head and smirked. "Oh, stop whining already."
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It's no longer a bunch of talking heads, is it? And I didn't put an action beat or full-on action around every bit of dialog. Tags are okay. One more note about context, before moving on. When there are only two characters having a conversation, context often becomes more obvious. If the conversation were strictly between Alfred and Sally, and you were relying on dialog tags for some of the exchange, you wouldn't need to repeat those tags because it would be obvious who is speaking as long as you observe the basic rules - new paragraph per speaker and such. For example:
"What?" she asked.
"Nothing," he said.
"Are you sure?" she asked.
"Yes," he replied.
Technically, could be rewritten as:
"What?" she asked.
"Nothing," he said.
"Are you sure?"
"Yes."
Now, onto my favorite part. Dialog tags as distraction. Remember, these things are supposed to be utensils, not the condiments, much less the food. Once you get going with that knife and fork in your hands, you don't much notice them anymore. Pursuant to that thought, when you use dialog tags, if you stick primarily to the garden variety - said, replied, asked - like the knife and fork, very shortly the reader doesn't even notice them there. They somehow ... work. The diner remembers the meal. The reader remembers the story.
Rather than listing the eight million ways to say said, I will point you to Aaron Lazar's excellent post from last year. Here's a great line from his post, and I whole-heartedly agree.
Never use anything but “said,” “asked,” or an occasional “whisper” or “mumble.” Once in a great while, if you feel you really need it, slip in a “spat” or “croaked.”
I'm personally okay with a "replied". And if you want to throw in the occasional flowery dialog tag, that's fine, but keep it rare. The thing is that when you do this:
1. "I don't wanna," he whined.
2. "You bastard!" she shrieked loudly.
3. "Don't do that," he lectured.
It does several things. First, the reader stops and reads the dialog tag. It's a distraction. Second, we are telling the reader how to interpret dialog whose intent is self evident. Readers like to use their imagination at times. Third, it appears that the writer is a novice, which doesn't help get you published if that's what you care about.
Now let me dissect what bothers me specifically about each of the above and make a suggestion.
"I don't wanna," he whined.
The dialog sounds like whining. I don't need the tag to tell me.
Better - He hung his head and kicked a pebble across the sidewalk. "I don't wanna."
"You bastard!" she shrieked loudly.
This is, O M G, this is too much. And I've seen this exact line somewhere. First, there's an exclamation point. Definitely tread lightly there, but given that it is there, it implies the speaker is shouting. So, shrieked is unnecessary. On top of that it's an adverbial dialog tag that happens to be redundant. I'm not aware of anyone who can shriek quietly. There's not much wiggle room there. So, we have an implied shout via an exclamation point, a beauty of a dialog tag, and an adverb.
Better - Her face was red and her hands balled into fists. "You bastard!"
"Don't do that," he lectured.
First. like #1, it sounds like the speaker is lecturing. But second, and more importantly to me, if you are going to use a dialog tag, make sure it is a form of speaking. Whispering, muttering, mumbling - those are forms of speaking that imply the tone - quiet and/or unintelligible. Lecturing is something a person does, not how a person speaks.
Better - He waggled his finger in front of my face. "Don't do that."
So endeth the diatribe.
