[zhoulin ]: - It is impossible to tell you what to say. If we tell you something, sometimes it will work very well, and other times it will be obvious that you just learnt to say that from someone, but are not using the phrase/complement in the correct situation.
For example, one of your friends who has known you for a long time, but ask you how your mother is doing. But if someone that you first meet asks you that, it is a very strange thing to say.
You need to judge the situation yourself. My experience is that you have to first of all "break the ice" (meaning remove the tension that exists when you first meet a new person) and then after that you can decide what topics are good to talk about and which are not.