It pays for writers to periodically revisit the basics. One of the writing gods we worship is Elmore Leonard (1925 - 2013), author of classic novels, many of which were turned into films: Hombre with Paul Newman, Valdez is Coming with Burt Lancaster, 3:10 to Yuma with Glenn Ford, Joe Kidd with Clint Eastwood, Get Shorty with John Travolta and Gene Hackman, Out Of Sight with Jennifer Lopez and George Clooney, and two dozen others!
Leonard is widely thought of as a master of dialogue.
Every serious writer has a copy of Leonard's Rules for writing. If you are a writer and don't have it, print this out and tape it above your desk.
1 Never open a book with weather.
2 Avoid prologues. (Yes, I'm guilty!)
3 Never use a verb other than "said" to carry the dialogue.
4 Never use an adverb to modify "said."
5 Keep your exclamation points under control.
6 Never use the words Suddenly or All hell broke loose.
7 Use regional dialect sparingly.
8 Avoid detailed descriptions of characters.
9 Don't go into great detail describing places and things.
10 Try to leave out the parts that readers skip.
11 If it sounds like writing, rewrite it.