I find so many helpful writing tips on Pinterest, and showing emotion through dialogue hasn't come as naturally to me as I thought it would as far as what the character is doing while either speaking or listening to whoever is in the scene with them. However, this post from The Writer's Handbook Tumblr blog, who shared it from One Stop For Writer's Pinterest board explains the way to show important emotions that for some reason haven't come easy to me.
Emotions such showing interest or disinterest in a character, showing nervousness, frustration or anger, (such as trembling or clenching their fists), sadness, etc. While I'm reading a good book for the first time, the plot itself holds my attention, which is exactly what our books should do for readers. When the writing is so well done that I barely pay attention to the grammar and writing style of the author the first time I read it, that is a story that I will read again from my writer's mind.