When writing dialogue, if you can manage to depict certain aspects of the written conversation through character motion, facial expressions, gestures, etc., then this can be an effective device. With that said, though, you also don't want to take away from the dialogue by infusing it with a bunch of "showy detail" that could hinder the flow and be distracting. You have to find a nice balance.
1) Keep the exchange natural.
2) Use gestures, facial expressions, character motion to convey certain things.
3) Use dialogue as a way to give some backstory.
4) Use dialogue tags (said, replied, acknowledged, uttered, surmised, etc.) only when necessary. It is not always necessary to use tags once you have established who's speaking in the conversation.
5) Use action tags as a means to "show rather than tell" aspects about a given situation or illuminate your characters.
Here's a little example of balanced dialogue:
Mark walked up to Susan and tapped her shoulder. "Hey, I haven't seen you around much. Everything okay?"
Susan turned away from her locker to face her friend. "No, not really. Issues at home," she said, grimacing.
"Aw, man, that blows. I hate it when the parents make my life miserable," Mark replied.
"Tell me about it." Susan's parents were going through an ugly divorce, leaving their kids caught in the middle.
"Well, I hope things get better."
"Yeah, me, too."