Once the conversation starts going I don't have too many problems, but starting it is always incredibly hard for me. What is funny is that it is actually easier if the other person is a rather extroverted one, because these type of people will naturally come up with things to say a keep things going. And I do manage to reply fairly quickly and appropriately, normally, but it's always as if I were dependent on the other person for choosing subjects and doing the first step.
Sometimes, before entering in a social situation, I do try to prepare a few sentences to say just in case, but it doesn't really work, it's difficult to act them properly when you are so tense, and even a good joke gets a bit spoiled if you say with a tone like you are reading a sentence to death
All of this naturally gets ten times worse when the other person happens to be a girl, in that case my mind remains blank like a white sheet of paper.
Sorry for any english mistakes, I am not a native speaker