Let me illustrate with an example of an over-use of dialogue tags:
“Do you want to come in for coffee?” she suggested.Do we really need any of the words outside the speech marks? No: we can manage perfectly well with just the speech, if the dialogue is strong enough. And that’s the key: your dialogue needs to be strong. If it is strong enough, it is strong enough to do the job on its own. Then you will need very few dialogue tags, and then usually only to show who is speaking. (Young children need more dialogue tags, as it is harder for them to follow who is talking.) Dialogue tags should show who is speaking, not how he spoke, unless that feels absolutely necessary.
“Is coffee all you mean?” he wondered.
“What else would I mean?” she scoffed.
“Well, just that I thought you might have some biscuits as well,” he responded.
“Aye, right!” she laughed.
Often, you can make the dialogue speak for itself, without any dialogue tags. Take a look at the same conversation re-written:
Carmelle looked straight at him. “Coffee?”Finally, just in case you haven’t quite got the point, here is an example of too many dialogue tags with the extra burden of unnecessary adverbs. (I've written about lazy adverbs here. Remember that there's nothing wrong with adverbs per se, just with their lazy use.)
“Just coffee?” He stared back, streetlight shadowing his jaw.
“As opposed to?”
“Well, biscuits. I was thinking you probably do a mean chocolate digestive.”
“Aye, right!” How did he manage to make the word digestive sound so desirable? Carmelle felt herself begin to blush.
“Listen,” she whispered conspiratorially.And here is how you could re-write that without dialogue tags or adverbs:
“What?” he interrupted eagerly.
“Nothing,” she replied, hesitantly, deciding that she was not going to tell him after all.
She leant towards him, her hair brushing his cheek. “Listen. I ...”Well? Please tell me you think the second one is better. Yes, the second one uses more words, but it uses them better. It uses verbs and action, shows us how the two characters behaved, allowing us to feel that we are there, to experience what they do. It draws the reader into the conversation, relegating the author (me) to a very appropriate sideline. After all, when you go to a puppet show, do you want to see the puppeteer?
His pulse quickened. “What?”
Carmelle took a breath. She paused. What if her informant was wrong? She shook her head, looked down at the stem of the glass pressed between her fingers. “Nothing.”