Scrape in one direction, don't scrape back and forth until a red dot (scratch) appears; The strength should be even and appropriate, and don't neglect it. If you have a headache or sore throat, sit and shave; Dizziness or chest pain should be scraped on the back; If the shoulder, back, lumbosacral and other places hurt, scrape them on your stomach. The number of scratches on the same part shall not exceed 20 times.