Once the two of you have got to know one another and are frequently hanging out, you can start to kick things up a gear. Show the guy that you're interested in being more than just friends by flirting with him - it might be just the sign he's been waiting for to ask you out.  Smile. Make sure to smile whenever you see the guy - this lets him know that you're happy to see him. Even if he's in a group of people, reserve the biggest smile for him. Make eye contact. Making eye contact is an essential flirting technique. One great tip is to look at him from across the room, then once he catches you looking hold his gaze for a moment before smiling and looking away. He'll be hooked.  Make physical contact. Another great flirting technique is to touch the guy in a more-than-friends kinda way. Lightly brush his arm when you're talking, give him a hug when you greet him, or gently mess his hair when you're joking around. This will give him the "I'm interested" vibe pretty quickly. If you have his number (if you don't, you should ask for it) you can text him things throughout the day to let him know you're thinking of him. You can send funny or flirty texts and if he replies with the same, you'll know you're on the right track.  For example, if he has a sports game or exam coming up, you could text to wish him good luck. He'll hopefully find this sweet and appreciate the fact that you remembered. However, you should also be sure not to overdo it. Remember the rule: if you send two consecutive texts without getting a reply, you should stop texting. It needs to be reciprocal. If the two of you have only been hanging out in group situations or in more formal settings (like school or work) until now, it might be time to invite him somewhere on his own. It doesn't need to be a three-course dinner in a fancy restaurant; it could be something as simple as coffee or the mall.  If he says yes, that's a pretty sure indication that he's interested in you, or at least that he really enjoys your company. Take it as a positive sign...

===
Write a summary of the previous text in Vietnamese:
Tán tỉnh. Nhắn tin. Mời anh ấy đi chơi. Nói với anh ấy là bạn thấy hứng thú. Hãy kiên nhẫn. Để ý tới cảm giác của anh ấy.