Rub a few drops of castor oil on your fingertips and massage your scalp to stimulate hair growth. Do this several times a week. For health long eyelashes, apply castor oil on your lashes every night before going to bed. In a couple of weeks time you should start to see results: naturally longer and thicker eyelashes! For thicker eyebrows rub some castor oil into your eyebrows each night before you go to bed and it will nourish and thicken your eyebrows.