And, having learned, from your own research, as much as possible about the interviewer's company. If detained, call before the appointed hour, if possible, speaking directly with the interviewer. Try to arrange another appointment. Darker clothes are always correct.
Light clothing tends to distract attention.
DON'T expect the employer to read your resume prior to your interview. If subjected to repetitious questioning by the same interviewer or other members of the company, be cordial about them, too. Be sure you understand what is meant. If not, ask for clarification. This indicated carefulness on your part, but DON'T overdo it or it can have a detrimental effect.