Pepper sprays, also sold to repel squirrels and other wild creatures, are effective skunk repellents. Spray them on trees and other areas where you've seen skunks. Ammonia also deters skunks. Soak old rags in ammonia and place them under your deck or porch to keep skunks from coming in.
The skunk is coming for food... could be a grub issue that you need to treat. They also like fallen apples... in case you have any fruit trees. But usually it's because there are grubs in the lawn they're digging for.