Place 4 ounces of dried herb (any part of the plant can be used) in a glass jar with a tight-fitting lid and add 2 cups of vodka. The alcohol helps herbs last longer. If you don't want to use alkohol you can use cider vinegar instead. Leave the mixture in the jar for 2 weeks. Shake the jar twice daily and keep it in a warm place.
Strain through a cloth into a brown glass bottle and make sure to keep it tightly closed.
The tincture should retain its effectiveness for up to 2 years.