2
Arrive on time or a little early the first day. Ask in advance when, where, and whom you will meet. Confirm that somebody will be there to meet you when you arrive.
Obtain and bring the phone number of somebody who can let you in. Get any special instructions, too.
Be courteous and patient with the receptionist and any security staff you meet on the way in. They can contact the right people and help point you in the right direction.