in my mind
asking closed questions is bad or questions that imply that you may not be worthy of her.
"can I have your phone number?" is like "I don't know if I am good enough for you because I'm insecure, am I good enough to have your number"
"do u want to come to town with me?

"
Its like putting her on the spot, pushing her into answering there and then.
also could imply> "Hey I'm only going to town so I can use as an excuse to see you and only if you are going."
What I would do:-
"what's your number" is like "yeah i've confident that I'm worthy enough to have your number, what is it"
"I'm going to town on saturday, call me if you wanna meet up"
Its all about comfort building. etc etc.