Confidence is attractive, so think positive thoughts about yourself. Tell yourself, “I've got this! I'm fun, easy to talk to, and a great person.” The more comfortable you are in your own skin, the more at ease you’ll be when you talk to the girl you like.  Additionally, keeping your cool will set the tone; she might get uncomfortable if you’re nervous and jittery. To relax before starting a conversation with the girl you like, try taking slow, deep breaths for a few minutes while imagining calming scenery. A joke can be a great way to break the ice, but you don’t want to be cheesy. If you’re not confident about your comedic timing, you could also just make an observation or ask a question. Just make sure whatever you say is open-ended, or invites a response from her.  For instance, you could say, “So how about our math homework last night? It was so long, I thought the problems would never end!” or just ask, “Hey! How’s your day going?” If you don’t already know her that well, introduce yourself. Say something like, “Hey, how are you? I’m Sam—I’m in your history class. What do you think of Mr. Jones going off on Tyler like that yesterday?” Think of a compliment that focuses on a quality you admire, like her sense of humor, style, or intelligence. Thoughtful compliments like these will probably make her feel more special than just saying something about her looks or body.  For example, say, “I saw the school play last week, and you did a great job! You have a gorgeous voice,” or “Congrats on acing another test! You’re so smart!” If you do want to compliment her looks, keep it respectful. Try telling her, “You have really beautiful eyes,” or simply say, “You look really nice.” You don’t want to lose her interest or make things awkward, so try to keep the conversation flowing. It might be helpful to think of topics to talk about ahead of time. Asking questions that prompt more than a simple “Yes” or “No” can also help keep the conversation going.  If you need to fill an awkward pause, try asking questions like...

TL;DR in Vietnamese:
Cố gắng thể hiện một cách tự nhiên và tự tin. Thu hẹp khoảng cách bằng một câu đùa hoặc câu hỏi mở. Nói lời ngợi khen sâu sắc. Cố gắng xóa tan khoảng lặng ngượng ngùng. Tránh thể hiện quá “lố”. Ẩn ý rằng bạn có tình cảm với nàng.