There are various causes of dark skin. Some are due to heredity, hyper pigmentation, skin disorders, sun rays etc. There are several home remedies which are very effective in improving dark skin which is given below:

1)    One can prepare a natural skin pack by mixing 1 teaspoon of milk powder, 1 teaspoon of honey, 1 teaspoon of lemon juice. Apply this pack on face and wash it after 10min.
2)    Take a raw potato and then cut it into fine slices and put it on the face.
3)    Make a paste using lime juice and turmeric powder and then apply it over the face.
4)    You can mix oatmeal with curd and tomato juice. You can use this mixture on the face and keep it for 15min and then rinse it with cold water.
5)    A paste of fresh mint leaves is also very helpful for treating dark skin. For this, make a paste of mint leaves and apply it over the face for about 20min. and must be continued for 15 days.
6)    One must drink plenty of water as it removes the toxins from the body and thus helping in clearing the skin tone.

Taking precautions and the above treatments would surely help in treating the problem effectively.