What to expect at US port of entry?

If your greencard is valid there wont be any problem. They probably ask how your vacation was. I am an aussie who moved to the states in the USA in 2006 and before i even got my greencard i got a travel permit cos i needed to go home and had no worries re-entering, same for the 2 year conditional greencard ( i travelled outside the country) came back and no worries, then when i got my 10 year greencard i did the same and no worries again. Now i am a US citizen. When you have a 10 year greencard i think you are not allowed out of the country more than 6mths at one time. You can visit visajourney.com and they have alot of your questions in there if you have any concerns. That was my guide getting me through the visa to citizenship process.