I think I've got a method of brewing green tea that works well for a variety of green tea types (y)
It uses about ~5g of tea...actually that's totally a guess, I either empty a pack of individually packaged green tea (most greens bought in China) or just eyeball a good thick layer that covers that bottom of the pot, for 100 - 150ml of water.
Start with a couple of slow infusions with cold water, which brings out the more delicate notes of the tea. Then gradually increasing the water temperature until boiling for subsequent steeps. Generally the steeping times get shorter as the water gets hotter. I can usually get 5 - 7 good brews in this fashion. Then I follow with some long steeps with boiling water to extract whatever's left but by then the flavor is less of a concern.
It's also funny that the teapot I bought mostly on a whim, the dragon kyusu, is the pot that best matches a type of tea. It really rounds out the flavor of green teas, and maybe thickens the body a bit too.