And here's some other lessons from Frozen:
Frozen does this nice trick where it hides exposition and boring plot points in dialogue that seems like something else. For instance, when Hans tells Anna that he has 12 older brothers, they do so simply in a bonding scene that quickly gets to Anna's unhappiness with her sister. And the fact that Hans has 12 older brothers is a crucial plot point for his motivation. So Anna will say yes to his proposal because she's lonely (which we already knew), but we'll learn later that Hans only proposes because of this issue.
Similarly, Kristoff drops the information about this winter coming from the North Mountain in small talk about the weather. Is there anything more boring than small talk? And yet, Kristoff does this in front of Anna, and it's crucial that she knows this. Hmmm... so this example isn't so much "hiding exposition" as "getting crucial information out in a natural way."
Set up the turn:
Dumb snowman Olaf is given some of the important revelations in the movie--that Kristoff loves Anna being the most important. It might seem like a cheat to have this sidekick suddenly provide the revelation. Except we've seen that Olaf is very observant, even if he doesn't know the significance of what he's observing. For instance, he talks about how Elsa is probably very warm and sweet right as he walks into some impaling ice lances and then he comments that he's been impaled. And so on: Olaf observes constantly, so it's not surprising that he's the one who observed Kristoff's affection.
Make a joke of it to get double the fun:
When Anna comes to Elsa's ice palace, she hesitates to knock, which shows--for once--some hesitation in her action. (Usually she's a charge ahead person; but where it comes to her sister, she's... a little torn.) And then Olaf makes a joke of it--"Does she know how to knock?"--which gives the scene another source of entertainment: Anna's character and the joke.
A hallmark of film structure is that you give your hero the same situation, with some crucial differences. Usually the difference is in the hero: he used to think his job was important, but now he realizes, blah blah blah. Frozen does some of this, but it also changes the world. So, we meet Anna at the beginning as someone who is locked out in the hallway while her sister is on the other side in the room; at the end, we see Anna locked in the room by Hans and rescued by... we'd expect her sister, but really it's Olaf, a representation of the sisters' childhood love.
I don't quite understand why Sven the reindeer makes Kristoff go back to rescue Anna from Hans. After all, Sven doesn't know the danger Anna is in; and he's not been set up like Olaf as the observant one. But just as the movie avoids talking about magic and trolls in this world (they just are, here are the rules you need to know, get over it), the filmmakers make a smart move here by giving Sven some agency--especially since he doesn't talk and can't explain himself. (Also, very smart of them to give Sven the personality of a dog, so that the reindeer-less viewers can understand their relationship a bit.)
Rooting for both sides:
When Hans goes to confront Elsa, the film pulls a good trick on us so that we can root for both Hans (the heroic prince, we think) and Elsa (the soon-to-be gay rights icon): they give us secondary characters that we can root against. So between Hans and Marshmallow, the giant scary snowman, we root for Hans; between Elsa and the evil duke's thugs, we root for Elsa. No one has to really suddenly change their personality totally--Elsa still wants to be left alone, Hans still wants to do the right thing (we think)--but we're able to root for both of them.
Interrupt a scene to change the direction:
When Kristoff and Anna are being married by the trolls, they don't have to totally object and start talking about how they don't want to be married. No, just give Anna an attack of her magical cold. (How convenient.) When Anna and Elsa are arguing in the ice palace, have Olaf or Kristoff walk in. Have Hans show up. Olaf discovers stairs so Kristoff and Anna don't have to argue. There are a lot of ways to keep a scene from just spinning its wheels over one issue by having another character interrupt, either changing the direction or giving weight to one side.
The importance of theme:
Sure, this movie is about sisterly love and how terrible it is to fall for the first guy you see; but both Anna and Elsa are struggling with parallel thematic journeys, from fear to love (Elsa) and from false love to real love (Anna).