Gather up documentation of bona fide marriage, even if you submitted it with your initial Adjustment of Status (AOS) application. Items like cards, notes, letters, emails, photos, and other mementos are helpful. Also include any bills or assets in joint names, like utility or telephone bills, bank account statements, tax returns, property deeds, and titles to automobiles. This isn't an exhaustive list of all of the possible items that can be used to prove bona fide marriage for your green card interview; in addition to these items, bring whatever else you think clearly demonstrates that you are in a true marriage.
Be prepared to present updated financial information. The immigration service will want to see that the US citizen spouse and immigrant spouse have a combined income of at least 125% of the federal poverty level.
Most recent three pay stubs
Last three tax returns
The movement of your bank account in the last three months
Current employer letter stating rate of pay, hours worked, and that prospects for continued employment are good.
Passport with non-immigrant visa (even if visa or the passport is expired)
Employment authorization card
Original birth certificates
Advance Parole documents (document which allows you to travel out of the country while you are waiting for the green card).
Prior to your marriage green card interview, review all of the forms and documents you filed to refresh your memory, since you may be asked about your responses to the questions on these forms.
On the day of the interview, arrive 15 minutes early, and be sure to dress neatly and conservatively. You don't have to dress very formally, but wear something that is clean, presentable, and business casual.
Answer questions honestly at your green card marriage interview. If you don't remember, say so. It's better to say you don't know instead of trying to make something up. There is no right or wrong answer to some questions. Sometimes the reaction you have to a question (e.g. body language, or wether you answered naturally), is more important that the answer itself!
The husband needs bring photo identification and passport.
The translator needs to be a US citizen or permanent resident.
It is your right to have an attorney during the interview. Make sure you have one with you.
It is also important to have an attorney prepare your forms and your package for Immigration. Obtaining a green card is a major event in someone's life and should be given the appropriate attention and importance.