What Not to Do:
"Lady Troodon what seems to be the problem?" sympathetically questioned the Knitting Velociraptor.
“I’ve had it with that amateur dialogue!” irately shrilled Lady Troodon as her feathers stood up.
"Oh my, that does look quite terrible," pontificated the Knitting Velociraptor as she stood on Lady Troodon's back to get a better view of the fanfiction that Lady Troodon was reading.
"The writer had potential," mused Lady Troodon thoughtfully. "It's not their fault—there's so much misleading writing advice out these days..."
"Perhaps they'll improve if you told them how they're doing it wrong," the Knitting Velociraptor chirped helpfully.
"I'm only one person in a sea of misguided writers," Lady Troodon intonated resolutely, "but I have to try. I'll make a tutorial."
Why That was Bad:
Said Bookism: “I’ve had it with that amateur dialogue!” shrilled Lady Troodon.
As put by storytelling wiki TV Tropes, Said Bookism is “Going out of your way to use any word other than ‘said’, even if the word is obscure and out-of-place”. Despite what you may have heard, using “said” is not an uncreative choice. The plainness of “said” keeps the reader’s attention on the line itself and the character who is speaking, as it should be. Many replacements for ‘said’ (such as “commented”) mean the exact same thing, but aren’t as discreet, thus drawing unnecessary attention to themselves.
The most sensible alternatives for “said” are simple ways to clarify to the manner of speech, (“whispered”, “yelled”, “mouthed”, etc.) and it’s acceptable to use them sparingly, but the more, uh, colorful substitutes for “said” (‘‘caterwauled”, “bemoaned”, “blubbered”, “shrilled”, “pontificated”, etc), should be avoided at all costs. If you consistently find it necessary to use flowery dialogue tags to get a character's point across, it’s usually a sign that you're not utilizing enough nonverbal communication, such as gestures and facial expressions.
Sometimes a word that isn’t a dialogue tag (“laughed”, “whistled”, “smiled”, “sighed”, “gestured” etc) is used as one. A few of these are actions (try to ‘smile’ a sentence--it doesn’t work, does it?), and others are non-speech sounds. This issue is often the result of incorrectly formatted dialogue.
Adverb Abuse: “I’ve had it with that amateur dialogue!” Lady Troodon said irately.
While it’s okay to spice up a dialogue tag with an adverb once in awhile, you might want to reconsider slapping an adverb onto every single dialogue tag in your story. In excess, adverbed dialogue quickly becomes an eyesore, and can also create redundancy.
“Said As” Syndrome: “I’ve had it with that amateur dialogue!” Lady Troodon said as her feathers stood up.
In my opinion, “Said As” Syndrome is probably one of the main reasons people might consider “said” overused. This happens when a beginning writer, likely very young, assumes that every line of dialogue must have a dialogue tag, but they also realize (to at least some degree) that nonverbal communication is important to conversations. A fix for this problem is demonstrated in the “improved” line below.
Improved Line: Lady Troodon’s feathers stood up. “I’ve had it with that amateur dialogue!”
What Should've Been Done Instead:
"Lady Troodon, what seems to be the problem?" asked the Knitting Velociraptor.
Lady Troodon's feathers stood up. "I've had it with that amateur dialogue!"
The Knitting Velociraptor climbed onto Lady Troodon's back to get a better view of the fanfiction Lady Troodon was reading. "Oh my, that does look quite terrible."
"The writer had potential," said Lady Troodon. "It's not their fault—there's so much misleading writing advice out these days..."
"Perhaps they'll improve if you told them how they're doing it wrong."
"I'm only one person in a sea of misguided writers," Lady Troodon said resolutely, "but I have to try. I'll make a tutorial."