The best place is in movies. Once you recognize subtext, your goal is to put subtext into your story. The thing is you can't do it intentionally. Subtext is about dialogue, more so than action because action speaks louder than words. In essence, you believe someone's actions more than you do their words.
Action always reveals the true personality of a character.
Or he states he likes dogs to a sexy woman who is holding a dog, but when he tries to pet the dog, he's apprehensive, his movements jerky. The dog snarls and he jumps.