Characters need to do two things: actions and dialogue. Your character's actions should be part of the plot. The dialogue, well, it needs to do two things: further the plot or reveal the character (if you took the Coursera class on plot, you've heard that phrase before). It sounds so simple, and yet dialogue is one of the things that the majority of writers struggle with. Personally, my biggest struggle is with giving characters distinct voices. I have yet to find a good resource to cheat your way into that, but here's an article to help with some other points of dialogue. I would like to draw everyone's attention to #10. The most common feedback I give here on Wattpad is in regards to easy to fix grammar mistakes of people writing dialogue. Please read and learn!
Rating: 4/5
Homework: write a scene with dialogue, but try to work in the tips given in this article.
Link: http://writetodone.com/10-easy-ways-to-improve-your-dialogue/