The actual format of an interview may vary, but most have similar components.
At least 5-10 minutes before interview time (no more than 15 minutes).
Firm handshake, eye contact, repeat the interviewer's name.
Ice breaking time within first 5 minutes of greeting.
10 minutes of questions about you. 5-10 minutes of your questions about their organization. After doing your research, you should have ready the attention-grabbing questions which will demonstrate your analytical ability, preparation, and incredible insightfulness before you ever step in their office.
Usually indicated by the interviewer when asking for any last questions. Be confident in last impression, ask what the next step is or when you will hear a decision, get interviewer's card, give firm hand shake with eye contact, and say, "thank you!"
Send a typed thank you letter within 24 hours of interview (only 20% of job applicants follow-up: this will say a lot about your professionalism!).