Make sure your resume is one to two pages long, no photo portrait, no graphic embellishments. Simple, clean, legible paragraphs clearly organized.
Include a short cover letter highlighting the two or three key points of distinction that make you a great candidate for the specific job. DO NOT attempt to explain those points in detail. Leave that material for your conversation with your interviewer.
Mentally prepare yourself to answer direct questions directly and to the point. DO NOT look at the ceiling, floor or side walls while formulating your answer. If you do not know, simply say so. I don't know, please explain!
Have you portfolio material sorted out and clearly organized before your meeting. DO NOT bring everything to your interview. Curate your design material and show no more than five minutes worth of design material. Leave some in your back pocket in case you are asked to expand your presentation. That is always a good sign the interview is going well.
DO NOT debate negative comments or observations. Thank your interviewer for the benefit of their insight, but you do not have to agree with what they say. Your interviewer may be testing your ability to self-control and your capacity for diplomacy and adversity management.
Smile and do not interrupt while speaking. Listen first and then reply politely and professionally.
Project a sense of ease, relaxation and self-control. As if you had been working there for years. Avoid appearing too anxious to get the job.
If you are being considered, they already like you enough to invite you in for the interview. Don't blow it by overreacting. Be yourself.