This ancient technique was used by primitive painters. It employs egg yolk, water, and pigments.
If you are short on pigments, gouache will work as well. The color of the tempera is very stable, and will look fresh for a long time.
It is ideal for decorating wood, over a dry primer such as gesso, for example.
As for the quantities, keep testing your mixture to find the right consistency for the surface you are painting:
paper, furniture, a wall...
The basic recipe is 1 egg yolk, ¼ eggshell of water, and pigments. Keep your mixture in a glass jar and use it up quickly.
There is probably a different recipe for every painter, but the following recipe is used by many contemporary painters:
a whole egg beaten with a whisk, a half eggshell of boiled linseed oil, ¼ eggshell of white wine vinegar,
½ eggshell of water, and pigment. The egg white is used as a binder, and the linseed oil makes the mixture more manageable.
To know more about egg tempera, visit this site: Eggtempera