With yellow undertones, the best hair color to complement your skin would be dark brown or even black. Avoid blond and red tones as these will bring out the yellow in your skin.
Most of the time I think people who have skin with yellow undertones would look best with a light hair color. Colors I think would look good are: blond, strawberry blond, light brown, or auburn.
you can dye your hair some dark colour, like raven or black or dark brown. but if you are too fair in complexion, it might make you look paler than usual. red might be a better option. don't dye your hair ash blonde as it might make you look very washed-out.
if your skin has yellow undertones you shold try light brown hair dye on your hair its look natural and also look good black dye on your colour tone its look good