If invited to an Iranian persons house, here are a few pointers to keep in mind.
Punctuality is appreciated, so try to arrive at the invited time;
dress conservatively; check to see if your spouse is included in the invitation, as conservative Iranians do not entertain mixed-sex groups;
check to see if your host is wearing shoes, if not, remove yours at the door;
expect to be shown into the guests room that is usually decorated with European furniture;
shake everyones hand individually;
accept any offer of food or drink, although first declining what is offered until your hosts insistence becomes greater – while this behavior may be deemed annoying and antiquated by foreigners, Iranians are very sensitive to what others will think of them and so this behavior has become an inherent part of their culture.
When at the table, it is crucial to keep in mind that Iranians are quite formal. Meals taken in the home are served on the floor and the fact that they are eaten without utensils does not automatically indicate a lack of decorum (it is only in more modern homes that meals are served on a dining table with place settings).
Here are some mealtime pointers: wait to be told where to sit; most tables are set with a spoon and fork only; eat only with the right hand; try a bit of everything that is served; there is often more food than can be eaten (Iranians like to shower guests with abundance!), so expect to be offered second and even third helpings; initial refusals will be assumed polite gestures (taarof) and not taken seriously; leave some food on your plate when you have finished eating; restaurants tend to have two sections, one for the "family" where women and families dine, and one that is men only.