How do you talk to characters during meet and greets?

Hey, all! I'm two weeks out from my first-ever WDW trip! My partner and I are in our late 30s and have always wanted to go to WDW since we were kids, so to say we're excited is an understatement.

While at the parks, we want to meet some of our favorite characters. We're also doing a couple of character dining experiences too. Some of the characters will be able to talk back to us (Mulan, Aladdin and Jasmine, Ariel) while others won't (Chewbacca, Chip and Dale, Goofy and Max).

What do you talk about with characters when meeting them? Do you just mention events/ characters from their respective movies to create conversation? Ask them questions? Is it harder to interact with the characters that don't talk back? Or easier?

I feel like I should have at least a few facts/questions/anecdotes at the ready for each character interaction, but idk if that's overkill. Thanks for your help!