I think one of the hardest aspects of writing is the dialogue. I’m currently reading a book with an enthusiastic ten fingers in the air. It has some good, solid advice in it. It is only 135 pages long so it won’t be a daunting task to read. I would advise reading it twice or maybe three times. I know I will, at least twice.
The author, James Scott Bell, says reading dialogue in screenplays will increase your knowledge. He uses examples from Maltese Falcon, which is a great screenplay. If you have a great screenplay, it more than likely will translate into a great movie. Yet, novel writing doesn’t have the same format as screenplays, but dialogue matters in both.
So for the purpose of focusing on improving your novel writing via dialogue, check out the book How to Write Dazzling Dialogue. Bell describes examples of poorly written dialogue, mediocre dialogue, and well-written dialogue where it is understandable. There are exercises you can do to improve your writing, which is also handy. I hope you find it as informative as I have so far.
Cheers and Happy Writing.