Quality dramatic scripts—I'm NOT looking at you, Law & Order—are excellent models for crafting realistic and meaningful dialogue. Writers of any genre who want to improve their skills in making page-people sound real will find loads of insight by reading scripts.

Image: two women talking
If you're serious about this challenge, choose a play you're familiar with and a single character from that play. Read the play from beginning to end, out loud if you can, but only the one character's lines, ignoring all other dialogue. Take notes on the ways in which personality and viewpoint are highlighted through skillful dialogue alone.
But there's a genre-crossing takeaway that gets less attention: action. Drama is, well, dramatic. In drama, nearly everything is action. Is tension. Is conflict. Manuscripts that fail to grab a reader often start too soon, with explanation, backstory, a word salad revving of engines.
If you're not sure where something starts—a manuscript, article, chapter—begin in the middle. Pull out the most dramatic moment, open a new Word doc (or whatever you use), start there as your draft beginning, and see what happens.