The herbs you are tincturing are known as the mark. Prepare the herbs by chopping or grinding them. Tincture several herbs together if you are creating a formula. Put them in a sterile jar with a tight lid, and cover them with brandy or vodka. Alcohol must be at least 50 proof to have good preservative qualities.
Vodka is the purest grain alcohol.
Strain after a month, first with a strainer and then through a clean undyed cloth, squeezing tightly. Pressing the herbs through a potato ricer while still in the cloth can be helpful. Bottle in sterile amber glass bottles. Label and date. Store away from heat and light.