advices needed!!!

I am about to go for an I-485 interview in a month. This is my second marriage and we got a 2 year old son also. I also applied for I-485 after my first marriage in 2003 but the first marriage turned sour after 3 months so we seperated and I didnt show up for the interview for the first application. I got divorced from the first marriage around the end of 2004. Any one give me some advices on what i shall prepare for the coming interview? what will the immigration officer ask mainly during the interview?? Much obliged and appreciated for any useful info.