Jim B:
Steps in Preparation - You just have to try it. Really. TO drink it, put the charcoal into water and stir slowly not to raise the dust before it gets wet as charcoal stains. For a paste put drops of water in and mix/test consistency before adding more. Try drinking a tea spoon of charcoal to water, any amount from 1/4 to a full glass.
How Much Is Too Much - I don't know
. Like any fibrous product use water with it. the more you use the more water to take. For up to a tablespoon use a glass of water. That amount would be good for serious situations like food poisoning other than that you would be using much less like a level or a heaping teaspoon to a glass of water.
What Type of Wood - Coconut shell is the best charcoal and I believe Eucalyptus is more popular.Activated Charcoal has been processed to make it more absorbent. In case of an emergency use whatever is available.