A big part of making eye-contact is just remembering that you're supposed to. If your natural inclination is to stare down at your shoes, try to practice when you're alone to realign your natural response to gaze down by focusing your eyes on faces. This can be done on television, in the mirror, or in a variety of other ways. One of the most readily available ways of practicing your eye-contact is to do it when you're alone, watching television. Focus on making eye contact with the characters on the screen and practicing the same skills to transfer them to your real-life conversations. Obviously eye-contact with faces on television will feel very different than making eye contact with real people. The point of the exercise is to practice the skill, not to approximate the feeling. If you don't have a television, try looking up YouTube vlogs and other videos in which people make eye-contact with the screen. This can make the eye-contact feel a lot more real. These videos are widely available and free, and are actually somewhat better at approximating what it's like to make eye contact during a conversation. If you have a close friend who you enjoy talking to, try using Skype or use another type of video chat to practice your eye contact. This is usually somewhat easier than in person, since you've got a computer screen between you. Again, it won't feel the same as making eye contact with another person, but you can practice training your eyes to drift toward the eyes you see back in the mirror, rather than deflecting them, if you practice looking at your gaze in the mirror. Just taking a few minutes before or after a shower can help you train yourself to make eye-contact, rather than avert your eyes. Autistic people, people with anxiety disorders, and others may find eye contact frightening or overwhelming. Don't sacrifice your ability to have a pleasant conversation.  Look at an area near their eyes, such as their nose, mouth, or chin. If they notice that you aren't making eye contact (which is unlikely), say...

How would you rephrase that briefly using Vietnamese?
Luyện tập ở nhà để nhắc bản thân phải giao tiếp bằng mắt. Luyện tập trên TV. Thử xem vlog. Thử trò chuyện qua video. Tập nhìn vào mắt mình trong gương. Học cách giả vờ giao tiếp bằng mắt nếu bạn có khuyết tật hoặc bệnh lý khiến việc giao tiếp bằng mắt trở nên khó khăn. Từ tốn.