Xin số điện thoại. Tự giới thiệu trong tin nhắn đầu tiên trước nếu cô ấy chưa có số của bạn. Nhắn tin thường xuyên. Chờ xem những dấu hiệu cho thấy rằng bạn đang đi đúng hướng. Lưu ý những dấu hiệu cho thấy cô ấy không hứng thú.

I'm interested in that, but I only have a few mins. Can you give me at most the first 500 characters of a detailed explanation in English about that?
Texting will only work if you know her phone number. It's hard to ask a girl for her number, but try to be casual about it. A simple "Hey, I don't think I have your number yet. Wanna exchange information?" should get the job done most of the time. When getting her number, avoid:  Getting her number from another friend. If she didn't personally give you her number, she's not going to expect you to text her. She could find it creepy that you got her number without asking her. Asking her over IM or