A few words about writing dialogue, folks. First, I am by no means a professional editor, but what I am is an avid reader and author of five books.
I know writing dialogue is difficult but, if we are to be good writers it takes a lot of effort to keep the story moving smoothly, logically, and continuously.
So here's the rub; if the dialogue is stinted, overly verbose, or not natural sounding it slows the pace of the story while the reader (me) fights his way through it. Sometimes I have to read it a couple of times to make sense out of it.
That is definitely a main reason why I lose interest and tend to stop reading the book.
When I write dialogue I picture the scene in my head and put myself in the place of the character speaking. I think "How would I say this?" then have an out loud conversation with myself and hear how it sounds. Does it run on? Is it realistic, common speech? Are there contractions needed? Does it help the flow of the plot?
If the answer to any of those questions is no, I will rewrite it until it meets that criteria.
Don't forget-It is OK to use common slang and curse words, as long as they fit the scene and are not just gratuitous. Instead of saying "I am going to go to the crime scene" why not say "I'm gonna go to the scene," thereby eliminating the excess verbiage and keeping the story moving at a good pace. The reader will easily be able to figure out where the character is going. Besides, not many people talk without using common contractions.
When using curse words, keep in mind the who are the readers of your work and make those words age appropriate to the reader AND the speaker. The words should provide emotion to the dialogue and scene and not be gratuitous.
Last point: You do not have to identify the speaker by name EVERY time he or she talks! If it is a somewhat long or complicated conversation, remind the reader who is speaking by using an identifying phase, such as "Detective Jones took a deep breath and said..."
In conclusion, remember, you may have a great plot and great characters, but without writing good dialogue you just might lose your reader, who might write a poor review of your work, and none of us want that.