This is the best advice on writing dialogue I've seen tbh. Also short and easy to understand!
As important as it is to create lovable, relatable, fascinating protagonists, it’s every bit as important to create antagonists who can stand in your character’s way, prevent him from reaching his goals, and, as a result, create conflict.
Why I Write Pulp Fiction by James Scott Bell
Find out these two vital keys your dialogue needs! www.raeelliottbooks.com
Answer all these questions and you should have a fully-developed character for your audience to connect with. A strong character can carry a weak plot; but a strong plot can’t carry weak characters