"Do you have a business card?"
"Could I have one of your business cards?"
"Can I have your business card?"

Responding to these questions are very easy. You can just say 'sure' or 'no problem.'

"Can I get your phone number or email address?"

"What is the best way to contact you?"
"Can I get your contact information?"

"Let me give you one of my business cards."
"My contact information is on my business card. Let me give you one."

"You can reach me by calling the number on my business card."
"My email address is on my business card."