First of all this is quite common, I think it can be related with approach anxiety but it’s completely normal – especially at the beginning- being nervous when you are talking to a girl. Let’s face it, is not easy talking to a complete stranger and trying to be charming/polite/smart at the same time. My advice for you is to work on your aa, this video can help you out with that
https://www.youtube.com/watch?v=gbjRPDV ... ature=plcp
About freezing up, when this happens most guys come up with a very personal question trying “safe” the interaction with “ Tell me your biggest fear” just keep it simple, less is more.
Here you have 11 tips can be useful in your situation.
https://www.youtube.com/watch?v=BWeQJmd ... ature=plcp
Good luck!