The Chief of Staff is the supreme authority in the office. But anyone on the team can be extremely helpful. You will ultimately be hired by the Chief or Staff Director, but be incredibly respectful with everyone you meet. Cater to the Scheduler and the general needs of the staff. You always go to them. You have much to learn from their guidance and suggestion.
Coffee & Meeting Success:
Helpful tips for effective outreach: Introductory Email Samples
Helpful tips for informational interviews: Informational Interview Tip Sheet
Use this library for incredible materials: Congressional Materials Library