The easiest bit of advice is to get out of the Loop; the city Chicago boosters won't shut up about is mostly out in the neighborhoods. Also: our real pizza is thin-crust.
Tavern style is what I always saw there (though I like deep dish). Also I'm surprised people always talk about deep dish pizza and not the clearly superior Chicago food: dipped Italian beef with hot peppers.
This is a bit of my own biases showing but I've found being very into deep dish or calling the loop "downtown" were ways to know who is new to Chicago
