First, read the English article below.

Fill a small dish with warm water, then squeeze a dollop of gentle hand soap or shampoo into it. Mix lightly until suds form on the surface of the water. Dish soap is generally not recommended, as it can irritate your skin when you need to use the sponge later. Baby shampoo and “gentle formula” organic shampoos work especially well, but most soaps that are safe for use on your skin or hair can be used here. 

Now, please write a short abstract for it in Vietnamese. Abstract:
Chuẩn bị một bát nước xà phòng ấm.