Appointments should be made well in advance. Confirm a week before and on arrival. When meeting people in a business context it's important to shake hands but only if your counterpart is the same gender. Men should wait to see if a woman extends her hand. If not, it's fine to nod and smile as an introduction. Visiting businesswomen should likewise take their cue from their hosts.
Stick to formal titles until your counterpart starts to call you by your first name. Men are referred to with the prefix Agha, women Khanoom. So Mr John Smith would be Agha-yeh-Smith, while Ms Sally Brown would be Khanoom-eh-Brown.
Conservative dress is recommended, but ties are not necessary. Few Iranians wear them, and they are actually illegal for officials of the Islamic Republic. Women should make sure head, ears and neck are covered with a scarf and the rest of the body with a long-sleeved loose dress.
You should always be punctual, even if your host is not. Be prepared to be kept waiting, especially by Government officials. Meetings begin with polite enquiries about health, family, and so on. Building a good personal relationship with your counterpart is important. Do not be put out by interruptions, which are normal. Be in no hurry to end the meeting. Try not to schedule back-to-back meetings, so that you have room to be flexible if things are going well.