Start brushing at the ends and slowly work your way up to the roots.  You can apply a leave-in conditioner or dry conditioner before brushing to stop tangles from forming while brushing. You will temporarily stand upside down so that you can brush the underside of your hair at the back of your neck. Brush your hair forward over the crown of your head and down to the tips, toward the floor.  Move all along the back of your neck and up to the sides of your head, beside your ears. You can also move sections of hair to brush hard-to-reach layers. Brush for 3-5 minutes. Avoid getting dizzy by standing back up slowly so that your body has time to adjust. Again, brush for another 3-5 minutes, moving all around the top of your head.  Brush in slow, gentle strokes to avoid hair breakage and to stimulate the scalp. Part your hair to brush in different sections as needed. Brushing your hair with a natural boar bristle brush can be done up to three times per day, but doing it at least once daily is recommended.

TL;DR in Vietnamese:
Chải tóc để gỡ tóc rối. Cúi người để rũ tóc xuống. Chải tóc bằng động tác kéo dài và nhẹ nhàng từ sau gáy. Từ từ trở về tư thế đứng thẳng. Lặp lại quá trình chải tóc như đã làm trước đó, bắt đầu từ chân tóc chải xuống ngọn tóc. Lặp lại phương pháp này mỗi ngày 3 lần.