There are various styling tricks that can be followed to make your hair look dark. But the best way to darken your hair is by following few natural steps. There are two types of hair color that can be darkened such as a light hair and gray hair.
To make the light hair dark, first take strong black coffee by brewing them and leave it become fully cold before applying it over the hair. As usual rinse the hair and use the mixture all over the hair strands and rinse your hair once again till you get the desired color. Next you can wash the hair again this time with a shampoo and condition it. Use the same technique once in a month to make the hair look darker without causing any damage. To make gray hair dark, first take two cups water in a bowl and add half cup dried sage. Make this mixture to boil and leave it to simmer for around 6-7 hours. Then you can start applying this mixture over the hair strands and leave it to dry on its own. Next rinse the hair as you did for the light hair and leave the hair to dry without using any hair dryer. Continue this method once in a month to maintain the gray hair dark. You can also try using henna powder to make the hair darker by mixing it with water and make sure to rinse the hair at last.