First of all, it sounds like you are confusing the Lawful Permanent Residency (Green Card) interview with the Citizenship (Naturalization) interview. The later will typically in a non-USC marriage case not occur until five years from the grant of the lawful permanent residence date which is the interview date if approved.
If you are sitting for a lawful permanent residency interview:
Every interview won't be the same, however, this will put you at ease. Just answer the questions, and don't ramble on. Bring all vital documents, and be patient and polite. It is usually wise to bring an extra photocopy of documents-- as most interviews--the examiner/adjudications officer does not have or can't locate some document needed so it is wise to make it easy for him or her to have that document and approve your case.
Everyone allowed in the room will be asked before the interview begins to raise their right hand and repeat an oath to tell the truth.
You will be asked your name, address, birthdate, and the names of your parents, and perhaps grandparents.
Verification of Identity:
You will have your passport if any reviewed, and birth certificate, parent's marriage certificate, driver's license, social security card, and the like of primary identification documents.
IMPORTANT FOR MALES:
Then, if you review your petition, typically, there are many questions that you have registered for the selective service? If not, do it ASAP and obtain a receipt as you could be found inadmissible for not doing so.
You will be asked if you have ever committed various crimes or immigration benefit fraud, been a public charge and so on. You can review your petition as that is what you will be quizzed on.
If you are going for a Naturalization/Citizenship interview N-400, then this first part is essentially the same--
however travel and residence (where you've lived, and travel outside the U.S.) these are relevant and you will be asked about the dates and time periods. This is because there are basic time periods to qualify to naturalize as a US Citizen. The interviewer would ask if any crimes have ever been committed, and to produce any documents. If that is an issue, and not minor traffic offenses-then you should consult an experience immigration attorney prior to your interview.
You will be asked to write a sentence in English, such as I drive my white car to work, or I can vote. I have the right to vote.
Then, you will be asked approximately 10 questions about history and civics, and usually who your Governor, Senators, and House or Representatives people for your state, and the US President, Vice-President--name them or some of them for the State representatives. The information on these questions and answers is available on the USCIS website. They have flash cards also.
This is based on interviews held in the Midwest, and NOT in Florida.
This is based on my experience handling an immediate relative adjustment and/or naturalization interviews.
If you would feel better, and you choose not to work with an experienced immigration attorney-- then take your petition and supporting documents and practice-- hold a mock interview prior to the interview.