1, understand the type of sunscreen: sunscreen is broadly divided into two categories, namely physical sunscreen and chemical sunscreen. Among them, the ingredients of physical sunscreen include titanium dioxide and zinc oxide, which are the most commonly used physical sunscreens, that is, UV-reflective ingredients. Typically, these ingredients are used in conjunction with chemical sunscreen ingredients for excellent and safer sun protection. Because physical sunscreens are milder and less irritating to the skin, they are suitable for people with sensitive skin or children. The easiest way to distinguish between physical and chemical sunscreens is to see if they look white after being applied to the face. If it is white, it is a physical sunscreen, because it has more particles and a thick texture, so it will form a white protective layer on the skin after application. If there is no white coating, it is a chemical sunscreen. 2, understand the SPF and PA: sunscreen packaging is generally marked with SPF and PA. SPF refers to the sun protection index, PA is for UVA ultraviolet rays. Usually, the strength of PA with + to indicate, more than a + said effective protection time extended. Specifically: PA + effective protection time of about 4 hours; PA + + + effective protection time of about 8 hours; PA + + + super protection. To ensure the best sun protection effect, it is best to apply every 3 to 4 hours and to apply 10 to 20 minutes before going out. 3, choose the right sunscreen products. spf is not the higher the value the better, according to the use of the occasion to choose a different sunscreen index, general indoor activities choose spf15/pa+-++ sunscreen products, a short time outdoor activities can choose spf30/pa++-+++ sunscreen products, if a long time in the outdoor activities to choose spf50/pa+++ or more sunscreen products. Secondly, the different skin texture, the degree of UV damage is not the same, according to the skin texture to pick a different water and oil formula to ensure absorption and sunscreen effect. 4, sunscreen to be comprehensive, not only the face to sunscreen, lips, ears, neck, hair also need to sunscreen. First sunscreen after isolation, sunscreen effect will be better. General sunscreen are chemical sunscreen, to be absorbed by the skin to play a role, if first applied isolation cream, the effect of sunscreen will be weakened.