This is an opportunity. Break it down.
What is it: A chance to talk to somebody on the inside who knows about organizational skills that can help you get again.
What is your goal(s):
a.) Get that knowledge
b.) Make a good impression for later hopefully.
You need to figure out beforehand what the state department does and how they go about doing it.
-Visas (the various types, F1, Student Etc)
-Foreign relations (Meetings and negotiations on various things from immigration to tarrifs to providing foreign aid and overseas citizen support).
-Research that the State department needs (How they familiarize themselves with foreign cultures etc, what tools they use, what computer programs "Lexis Nexis?" they use and who does that. Perhaps even ask to speak to that person or persons in other departments/job shadow)
-Employment requirements (It is a pain in the ass to get a government job like that. Express interest and ask how you as a diligent student can apply yourself to be considered for one).
-Skill requirements (Ask what skills he or she believes the department finds valuable and how you can build or already have built those skills).
-Laws and policies that guide and determine what the Department must do.
Here's the real trick: appearing confident and interested without looking like you're trying too hard on this one.
-It's got to be a pleasant enough experience for the person you're going to be around as much as it is for you. Easier said than done,but conversationally important.