If you ended your first date with a promise to call, follow up within the next few days.  If you reflected on the date and realize you're no longer interested, give her the courtesy of letting her know you don't think it's going to work out. If you want to continue the relationship, don't play hard to get. Be consistent in your communication. Once you've gone on a few dates, a great way to get to know each other better is to introduce the girl you're interested in to your friends. If they hit it off, you might be encouraged to take the relationship to a deeper level. Consistency is important when you're dating, but you should also throw in some romantic surprises. The surprises will depend on the personality of the girl - maybe she'd love it if you cooked dinner for her, sent her flowers at work, or planned a fun weekend trip. She'll be impressed by your thoughtfulness if you mix it up sometimes.

How would you rephrase that briefly using Vietnamese?
Gọi cho cô ấy như đã hứa. Giới thiệu cô ấy với bạn bè. Tạo bất ngờ.