well am glad this is brought up here and Jon has helped out to clarify some points however what if you make an assumption and you don't know how to follow it up, such as the girl responds says she is from Paris or Milan...I don't know much about Paris, what do you say
You still have to make a statement based on her answer or you will be just jumping from topic to topic which means you wont be in a proper conversation. People may think they dont know anything about her answer but if she said 'Paris' for example im sure something will come into your head! You could say "I dont know anything about Paris but I imagine........." you can say anything and she will then tell you about it.
I don't want to keep on making assumption which are wrong, surely that is bad right to get it wrong...
It doesn't make a difference. If you get it wrong then she will give you the correct answer and you can go from there using the new information she has gave you.