First of all, we have to judge whether we are cold skin or warm skin. We can look at the color of the blood vessels of the arm to distinguish.
If the blood vessels are mostly blue-purple, you are cold skin, so you can choose some pink-tone foundation. If the blood vessels are mostly green, then you are warm skin, you can choose some yellow tone foundation. If the color of the blood vessels is purple and green, you can choose between a pink and yellow foundation.
If you have the conditions, you can apply the cool and warm foundation to the inside of the arm. After a few minutes of painting, observe the color of the foundation. If you run out of skin and become natural, it is the color that suits you.
Because the color and tone of each brand are not exactly the same. We can also judge by the color of the neck and face, the color number closest to the skin of the neck and face must be suitable for you.
Because the oxidation degree of each brand of liquid foundation is not the same, some liquid foundation color is very suitable, but the face is oxidized and blackened for a long time, so it is recommended that you really go to the counter to try it.