Two thorough guides to making essential oils at home are available online at essential-oil-mama.com and Aromatherapy At Home. The former guide notes that homemade essential oils may have decreased efficacy in therapeutic treatments compared to professionally extracted, pure essential oils. Homemade essential oils are often used in soaps and perfumes.
Essential-oil-mama.com provides detailed information regarding the many procedures for making homemade essential oils. The three most common methods used to make essential oils are distillation (collecting the oils using steam), expression (mechanically pressing a plant to release the oils) and extraction (pulling the oils from the plant using a solvent such as alcohol), and each of these includes a variety of different techniques. Distillation is the only process that yields true essential oils.
Although Aromatherapy At Home also includes procedural instructions, one of the website's most helpful elements is its section on which flowers and herbs to use when making essential oils. The site points out that it is important to harvest plants for essential oils at the right time to get the purest possible essential oil. Most parts of the chosen plant can be used, excluding the woody stem. The website also includes suggestions for mixing different essential oils, such as a combination of lavender, peppermint, lemon balm and marjoram or a mixture of rose, jasmine, coriander and lemon peel.