Make sure you are using a multi-blade razor, such as Gillette Venus Deluxe Smooth Platinum Razor ($15) and replace the blade after five or six uses. An old and rusty blade can often cause ingrown hairs. Also, always use shaving gel or cream and shave gently in the direction of the hair growth. Lastly, pat on Fur Oil ($52) to prevent and treat any existing ingrown hairs.