Article in English: If you plan on asking your girlfriend if she wants to have sex, then you should do it in an intimate setting -- not while you're splitting a cheeseburger. So, if you're ready to have sex, and it turns out that she's ready to have sex, then what does this mean? Condoms. Don't show up at her place, or invite her to yours, knowing that there's a chance you'll have sex without being prepared.  Don't show the condoms to her or creep her out, but have them at your disposal just in case she is ready. Nothing will ruin an intimate moment more than a trip to the drugstore. Once you're prepared for action, you should reach a point where you're intimate with your lady. This means you should take her out, make her feel special, and then get some time alone with her. How intimate do you have to be? This depends on how fast things progress. If you're already in the bedroom and part -- or most -- of your clothes are off, then it is time to ask her for confirmation that she is ready to take things to the next level.  If you're just kissing on the couch and she doesn't make any more moves, it may be too soon to ask. When the time is right, stroke your woman, look into her eyes, and say, "Are you ready?" Don't say, "Wanna have sex?" or "Wanna get it on?" Or she won't take you seriously. Make it clear that you're asking whether or not she's ready for sex, and wait for a response. She'll appreciate that you can be subtle and open at the same time. Obviously, make sure your girl is sober when this decision is made. The worst thing you can do is pressure her into doing something she'll regret later when you're both under the influence. If she says she's ready for sex, then do a private cheer, get your condoms, and get ready to get it on. And if she says she's not ready, respect her decision and let her know that you're perfectly cool with that. Tell her she's worth the wait and that she can take all the time she needs. Be a gentleman. If you get angry or try to pressure her, then she'll be second guessing your relationship right...

Summary in Vietnamese:
Chuẩn bị. Giữ sự thân mật. Chỉ hỏi khi cô ấy thoải mái. Phản ứng một cách thích hợp.