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Some stories might work best with simple dialogue descriptors like "said" or "answered." Others might sound great with more descriptive words, like "protested" or "exclaimed." Your story might even work with a mix of the two! Go with whatever sounds best to you in the context of your work. No matter what you choose, make sure you don't use the same descriptor over and over. This gets repetitive and boring for the reader. It should provide information to the reader about the story or the characters. Dialogue is a great way to prove character development or character information that your reader might not otherwise get.  Don't do small talk about the weather or how each character is doing, even if that's something that comes up a lot in real conversations. Now, a way in which small talk would be well used is to build up tension. For example, a character really needs certain information from another character, but the second character insists upon the ritual of small talk, your reader and your character will be biting their nails in waiting to get to the good stuff. All your dialogue should have a purpose. As you're writing dialogue, ask yourself, "what does this add to the story?" "What am I trying to tell the reader about the character or the story?" If you don't have an answer to those questions, scrap the dialogue. This is a big one that a lot of people have the tendency to do. You think, what better way to get information across to my reader than by having my characters discuss it at length? Hold it right there! Background information needs to be added sporadically throughout the story.  For example of what not to do: Jane turned to Charles and said, "Oh Charles, remember when my father died a mysterious death and my family was turned out of our home by my evil aunt Agatha?" "I do remember that, Jane. You were only 12-years-old and you had to drop out of school to help out your family." A better version of the above might go something like: Jane turned to Charles, her lips set in a grim line. "I heard from aunt Agatha today." Charles was taken aback. "But she was the one that kicked your family out of your house. What did she want?" "Who knows, but she started hinting things about my dad's death." "Things?" Charles raised an eyebrow. "She seemed to think his death wasn't natural." Conversations, especially in stories, are layered affairs. There's usually more than one thing going on in them, so you want to make sure that you capture the subtext of each situation.  There are lots of ways to say things. So, if you have a character that you want to say something like "I need you," try having them say as much, without actually saying it. For example: Charles started for his car. Jane placed a hand on his arm; she was chewing at her lip. "Charles, I...do you really have to go so soon?" she asked, withdrawing her hand. "We still haven't figured out what we're going to do." Don't have your characters say everything they're feeling or thinking. That will give away too much and won't allow for any suspense, or nuance. You want your dialogue to be interesting and to keep your reader engaged in the story. This means skimming over background conversations, like people at the bus stop discussing the weather, and getting into the meaty conversations, like Jane's confrontation with treacherous Aunt Agatha.  Engage your characters in arguments or have them say surprising things, as long as these things are in character for them. Dialogue should be interesting. If everyone is agreeing or asking and answering basic questions, the dialogue will get boring. Intersperse your dialogue with action. When people are having conversations they fiddle with things, laugh, wash the dishes, trip over things, and so on. Adding these things to the dialogue will make it come alive. For example: "You don't think a healthy specimen like your daddy would've just sickened and died," Aunt Agatha said with a cackle. Jane clung to the shreds of her temper, replying "Sometimes people get sick." "And sometimes they get a little help from their friends." Aunt Agatha sounded so smug Jane wanted to reach through the phone and wring her neck. "if someone killed him, Aunt Agatha, do you know who?" "Oh, I've got a few notions, but I'll let you decide on your own."
Match your dialogue verbs to the tone of your story. Move the story forward with your dialogue. Don't info dump in your dialogue. Add subtext. Mix it up.