Confidence is one of the most attractive qualities a person can possess. You don't have to be super sexy or built like Chris Hemsworth, either. All confidence requires is a firm belief in your own self-worth. If you believe it, that girl you like? She's going to believe it, too.  It takes time and a little effort to build your confidence, especially if you're starting from a low point. Even if you don't believe in yourself, pretend like you do. Faking confidence actually tricks your brain into believing that you are confident!  Stand up straight when you're walking, like you matter. Take up space like crossing your ankle across your knee when you're sitting. Leaning nonchalantly against a nearby surface. Avoid crossing your arms across your chest, or not making eye contact when you talk to people. Both of these are defensive gestures. Part of being confident is being yourself and being okay with who that is. Trying to change yourself to be someone else isn't going to work with her. She's going to see that you're not comfortable with yourself and that you're lying about who you are and she won't be pleased.  Show what makes you unique and why you're interesting. You don't have to walk around wearing a pocket protector (do people do that anymore?), but you don't have to hide that you're interested in computers. She will accept you and if she doesn't.. she's probably not worth your time! Don't try to be someone else, especially if you're trying to be the person you think she wants. If she isn't interested in the person you are, she's not the girl for you. It's hard to attract the girl that you like when you overwhelm her with your smell and your greasy hair. Try to shower at least a couple times a week and use soap. Wear clothes that have been recently laundered. Reusing jeans and trousers is fine, as long as they aren't super dirty, but change your shirt each day.  Be careful about using aftershave or cologne. A little goes a long way! You don't want to approach the girl you like in a cloud of cologne. Keep it...

How would you rephrase that briefly using Vietnamese?
Xây dựng sự tự tin bản thân. Hãy là chính mình. Luôn duy trì vệ sinh sạch sẽ. Có cuộc sống của riêng mình.