Hi Stepen,
I'm not sure if different styles have different criteria but in the TCM that I practice and am still learning in my Masters of Chinese Medicine program that I'm finishing in grad work, there is no particular place other than as many rand places as possible on the location that you are applying cupping. I remember the first time receiving it for mild insomnia, I couldn't imagine how it would help as I received it and I slept like a baby that night. I'm sure there are probably location rules to some treatment patterns but we weren't taught any.
The way I was shown in China was that for sore muscles they are placed over the belly of the muscle and along the edge of the muscle. Or you can use one large cup and slide it very slowly over the muscle leaving it sit for a couple minutes in areas you feel energy stagnation.
For fatigue, flu, chronic conditions they are placed along the meridians.
I recently bought rubber cups and I like them. However they only came with 1 of each size. This is not enough to do a treatment. I would recommend getting 4 sets when ordering. For my sessions, that I do following what I was taught at the hospital in China, I use usually 6 of the large and medium sizes at a time.
I don't care for the plastic ones with pumps. Perhaps too traditionalist but also I have been cut by them and know many others who have been scraped or cut. I am using the rubber ones for good suction and to eliminate flames from the rooms.
I am not train in this professional way, but in my country I been do cupping seen i am about 13 year old. I like to use the original way with the flame and the glass cup.Because, when you use the plastic cup with the pump, can't tell where the areas that have energy stagnation. With the flame when the areas that have energy stagnation when you apply the cup, it will draw up right away and the color will be dark red, same go with gua sha.