Think CS. Not just "Citation Shares," but Customer Service. Be excited, friendly, and personable. Be prepared to tell them about how you'd go the extra mile. Tell them about any customer service experience you have. Study Jepp charts.
Have a good answer for these two questions (good advice for any interview):
Tell me about yourself. (although not technically a question.
Why do you want to work at Citation Shares?
Study aviationinterviews.com gouge.