Though extracting oils by steam distillation and other methods is almost prohibitively expensive, we are spared this cost by the wide availability of essential oils and synthetics on the market today.
Many so-called “essential oils” are actually synthetic; this does not negate their use in magic, however.
If they smell good, use them.
Essential oils are used in numerous ways. They are worn on the body, rubbed onto candles, dabbed onto sachets and poppets, added to baths, burned on charcoal blocks, and smeared onto roots.