In the Garden of Eden, foods were synonymous with herbs. Every food has medicinal properties and herbs represent the more potent aspect of plants which can bring about healing in the body. Herbal healing is performed by matching the plants which have certain affinities with the person's symptoms.
The current information we have on herbs is twofold. For one thing we can draw on the traditional uses of herbs from many cultures and find plants that suit our needs. The other growing aspect of herbal healing is in the identifying of active ingredients and how these ingredients, when concentrated, have marked affect on the biochemistry of the human body. The latter confirms the former. For example, licorice root has its folklore about longevity and now we find it has chemicals that enhance adrenal gland hormones.
Some branches of herbal healing look from a more spiritual perspective, seeing the plant as having a consciousness of their own. Which ever the school of thought, herbs will always be somewhat mysterious. Some plants cannot be isolated to their active ingredient and work with a synergy found only in the natural source. While we can mimic the action of an ingredient by creating synthetic drugs, we may be missing the true benefits of the herb itself.
Today we find herbal preparations that are marked "standardized extract". This kind of formulation guarantees the concentration of an active ingredient to be at a certain level. In this case we get the ingredient at a dose which has been proven to exert a specific affect in clinical study and we also get a certain amount of the crude plant for the synergy of ingredients from the natural source. In my opinion, the best of both worlds.
Herbs are used in healing topically on the skin with salves, balms, ointments, and compresses. Herbs used in this way will absorb into the body through the skin. They can be taken internally in the form of a tea, alcohol/glycerin extract or tincture and these days in capsule. Herbs can be used fresh from the plant or dried and preserved by a variety of methods. Do your own research on which herbs are best suited for you, and the methods for using them. If you are currently on medication it is always wise to consult with a knowledgeable practitioner who is aware of herb/drug interactions.
Teas are perhaps the best way to begin introducing yourself to herbs. While some herbs may have very bitter or unpleasant tastes, this is part of the medicinal property that may be missing if the herb was taken by capsule. As a general rule, herbs considered to be tonics are safe. Always use sensibility, sound judgment and respect for the medicinal properties of an herb, taking as it is needed, in the lowest dose required to have an effect and in harmony with other healing modalities.