If your nails are yellowing due to some kind of fungus-related infection, tea tree oil is the best home remedy to try. Tea tree oil is a natural fungicide and has antiseptic as well as antimicrobial properties that will help fight infection and restore the natural color of your nails. Apply pure tea tree oil to your nail beds using an eye dropper. Leave it on for a few minutes, and then rinse it off with lukewarm water. Do this twice daily for several months until you notice improvement. Mix equal amounts of tea tree oil and olive oil. Apply the solution to your nails using cotton balls. Do this twice daily for several months.