The Indians are credited with discovering the healing properties of Goldenseal, and passed their knowledge of the plant on to the early pioneers.  It was considered a miracle cure-all, and was becoming scarce even in the early 1900's because of over-harvesting.  It remains a very popular herb today, largely because of it's reputation as a drug test mask.  However, through science and the advent of synthetic drugs, it no longer holds the importance as a medicinal herb that it once did.  It is also ridiculously expensive, so do check out other herbs for any specific ailments before investing a fortune in a Goldenseal remedy. 

Having said that, Goldenseal does have some uses in the herbal medicine cabinet.   It is most commonly used as an eyewash and mouthwash, and is still prescribed by herbalists for canker sores and cracked lips.  It also seems to have some merit in cases of  sore throat, clogged sinuses, congestion, diarrhea, poorly healing wounds, psoriasis, acne, inflamed mucous membranes (such as in the mouth), fungal infections such as athlete's foot and yeast infections, and as a digestive aid.  It is often packaged with Echinacea as a treatment for colds and flu, but in reality, the Echinacea is probably the ingredient that causes the symptom relief.   

For external use, make an Ointment or buy a commercial preparation and cover the area in question thoroughly.  There is fairly strong evidence that Goldenseal does indeed speed the healing of wounds and abrasions.  

For internal use, and as an eyewash and mouthwash, make a Tea.  Drink 1 cup up to 3 times per day for congestion, clogged sinuses, and diarrhea.  Use the tea as a gargle for sore throat, or dab the tea solution into the eyes as an eyewash.  Do not overuse this herb internally, as it can cause unpleasant side-effects, and discontinue use altogether when the symptoms retreat.  

For yeast infections in women, make a strong Tea and use as a douche for relief of symptoms. 

Do not use Goldenseal of you are pregnant or breast feeding because it can cause uterine contractions.