Start with white paint as the base
Add a small amount of yellow paint
Add a tiny amount of red paint
Mix well
Add a very small amount of brown paint if needed
Adjust with more white to lighten
Adjust with more yellow to warm the tone
Adjust with more red to deepen the tone
Adjust with more brown to make it more natural
Test the color on a separate surface
Repeat small adjustments until the desired skin tone is reached