Elmore Leonard, famous crime novelist, contended the writer was "sticking his nose in" by inserting a verb with dialogue, so it was best to use the least intrusive verb possible. Many writers agree because "said" certainly doesn't draw attention to itself or distract readers from the story.
I don't disagree. I'd include "ask" as well because it's nearly as invisible as "said" and works better with questions. However, I object to an absolute use of "said" for two reasons:
- "Said" attracts adverbs.
- Sometimes how the character delivers the dialogue is important.
My other reservation about using only "said" is that sometimes how a character delivers a line is crucial. For example, maybe your protagonist says something outrageous about her boss in the middle of a meeting. Whether she mutters it under her breath or shouts it out loud changes the entire scene.
Since I had two reasons not to stick solely to "said," here are two tips on what to do instead.
If you're using another verb, make sure it's physically possible to talk while doing that. When editing, I've run into characters that grin, laugh, or gasp a line. Try one of those while actually talking -- I dare you. Instead, let your character complete the action and then talk. For example:
Tim grinned. "Go ahead. I dare you."
The second tip is to make your dialogue do the work. Rewrite so that the words, sentence structure, and rhythm indicate how the character says the lines. You won't need a verb like "snapped" if the sentences come in short, staccato bursts. An adverb like "incoherently" is unnecessary if your punctuation, sentence structure, and word choice show that the character can't string together coherent sentences.
So what's the final takeaway on never using a verb other than "said" with dialogue? Never say never.