Basically what Mariasemuel wrote... take multivitamins, eat lot of fruits and vegetables (balanced diet), wear sunblock every, exfoliate your skin using facial scrubs, tone your face using lemons
From my experience, when your liver has to work hard, your skin tends to yellow. After I drink or get sick, I noticed discoloration also.
Try Skin 79 brightening mask and Shiseido White Lucent.