An essential oil can be made of any strongly scented flower or pleasant spice. Roses are the most popular as is cinnamon and sage. Essential oils can be purchased and then diluted in jojoba oil or vegetable oil, or you can make your own. Commonly used vegetable oils include safflower, sunflower, and olive. Jojoba oil is the best to use since it is actually a wax and does not spoil. For essential oils, sweet almond oil, not bitter or extract, is commonly used with Vitamin E as a natural preservative.