Plan Your Time to Get There

Use a map ahead of time and know the exact location of the interview site.
Consider taking a recon visit on the weekend before your interview date.
Leave at least a half-hour early to ensure you arrive on time. Promptness to an interview is expected, and leaves an important first impression.
Be sure to have cash (and coins) to pay for parking as some companies may not cover it. (This is a possible payoff from your weekend recon visit)
Park as close as possible so that you will stay cool on arrival.
Do not present yourself for the interview more than ten minutes early; however, assuming you arrive sooner than that (and you should), wait in your car, go for a walk, or review your resume and/or questions one last time. Keep track of your time.