The proper way to measure coffee is by weight. If you are really serious about coffee, then you should invest in a scale that can weigh small portions of coffee accurately. A good scale is indispensable when blending your own coffee in small amounts, unless you want to spend a lot of time counting coffee beans. You can measure coffee by volume, but you lose a lot of accuracy because of varying bean densities and having to rely on visual estimation.
The proportion of ground coffee used in relation to the amount of water used, constitutes the brewing ratio. After the coffee has been brewed, the amount of solubles that have been extracted in relation to the amount of water, constitutes the drinking ratio. The brewing ratio usually determines the drinking ratio, but it doesn't have to. Hot water can be added to the infusion after brewing to reduce the concentration and flavor intensity of the brew, thus changing the drinking ratio. Experimentation will lead you to your own personal brewing and drinking ratios.