Pretty straightforward, ask questions to gain insight to make sure you know your trade. Review your basics you should be good. If they ask you a question and you do not know the answer don't try to bull crap.
I applied online. I interviewed at Georgia-Pacific in Sept 2013
Interview
The process is very slow starting with a short questionnaire. then a trip to job service to do a personality test. Next comes a skills test and finally a group interview. the total process takes about 4 months
Interview questions [1]
Question 1
How you dealt with a disagreement with a former boss