definitely need to outstand yourself from BAIDO ZHIDAO, how to make answers more professional is critical. Maybe, divide into different parts. one is only used to post leisure topics and the other used to post professional topic. sorry, cant type chinese right now. Another suggestion, ask user to specify thier professional fields and their interest, so on the homepage, only show the relative topics. I am thinking that people who use this website is definitely looking for some high quality answers, otherwise why bother using it.
Another one, do a survey to see what kind of people are the majority