Sit in the car, be calm, take some time to set yourself ahead of entering reception.
Put on a clean suit. Wear it sharp and clean.
Do not use unprofessional terminology.
Make first impressions count and offer warm greetings with all you speak to.
Try not to oversell who you are.
Suggestions for those looking for employment:
"Create job-gaining materials and forge job hunting skills. As soon as your job goals are targeted, your CV and application letters can be customised to submit your talents so they tally with the requirements of possible companies."