If you are invited to an Iranian's house — and trust me, you likely will be — there are a few things you need to observe. First, bring flowers or pastry for the hosts, and always apologize for the inadequacy of your gift (it’s the polite thing to do according to ta’arof). Try to arrive early or at least on time; punctuality is important in Iranian society. When you arrive, check to see if the host is wearing shoes. If not, remove yours at the door. Show respect for the elders by greeting them first, and shake everyone's hand individually. Always wait to be told where to sit.
Note that meals taken at home are usually served on the floor and eaten without utensils (it is only in modern homes that meals are served at a dining table with place settings). Remember to eat with your right hand and try a bit of everything that is served. Most tables are set with a spoon and fork though (no knives) — if you don’t feel comfortable using your hands, don’t be embarrassed to use the utensils.
Iranians like to shower guests with abundance, so there is often more food than can be eaten. Expect to be offered second and even third helpings; initial refusals will be assumed to be polite gestures (again, in adherence to ta’arof) and not taken seriously. If you are full, simply leave some food on your plate to indicate that you have finished eating.
Social Etiquette in Iran: How to Greet People
