My husband and I use gua sha on each other and neither of us have any "formal" training. There are several books and sites that can help you learn how to use this for yourself properly. Gua Sha is a "folk" remedy because it is used by everyday "folk" in China and other places. It is simple and painless (I even think it feels good). It brings release to tight muscles and relief to painful and stressed areas. The scraping marks last usually about 2 days for both my husband and myself. I have heard of scrapings lasting longer.