I like using dialogue to help establish a character's personality. It's easier than writing two or three paragraphs of a character's inner thinking all the time. Having them speak and express themselves can go a long way with less effort.
If I were to add anything to this article, it would be that no character stands in place and delivers their lines. They're usually sitting or doing something. If it's dialogue taking place in the kitchen between two characters, it's a good hunch that they're doing something at the same time they're speaking to each other. Weaving their actions, words and the tone and expression on their faces can paint a vivid picture that if done well, will put the reader right there in the room with the characters.
And unnecessary dialogue (stuff that isn't important and would slow down the story) could be boiled down to a paragraph giving the general idea of what the characters discussed. And what exactly is it? I say it's like porn. You know it when you see it.
Love reading your articles. Always looking forward to the next one.