Dialogue

So I learned I've been doing dialogue wrong this whole time.  Okay, so maybe I can say I've been doing dialogue in a less professional manner than I should without knowing it.  I watched a video posted by BookBaby/Autocrit about dialogue, and it showed me how I should be doing it according to many editors and publishers.  I knew that adverbs were to be minimized if not avoided entirely in strong writing.  Too many -ly words can lead to weaker instead of stronger writing, and the Harry Potter series was improved as J.K. Rowling worked on trimming them back.  So I knew that I shouldn't tag dialogue with phrases like "said happily" or "asked sadly."  But it seemed to me like the word "said" was such a dry, dull word.  I've heard again and again that redundancy is the kiss of death for good writing.

Well, it turns out I was wrong.  I submitted my first manuscript chock full of characters that screamed, purred, mocked, or murmured their words.  Instead, I should have erred on the side of boring and redundant.  It turns out that one is best served having characters that said this, said that, answered this, and--occasionally--shouted or whispered something when the volume becomes important.  Who knew?  The dialogue tags are simply to show the reader who said what and then fade into the background.  Instead, one should concentrate on beefing up the dialogue, so it's obvious who is screeching, purring, etc.  Not only that, but one should avoid having the characters speak and do something that can't be done while someone is speaking like laughing or coughing words.  Good to know.  Now, I'm wondering what other bits of writing wisdom I'm missing.