In comments, Mae writes,
i have just bought pigment powder and am preparing wood (with gesso) to make an icon type painting…can you give me any tips on mixing egg tempera…the type of oil etc.
Prepare pigments as follows: while wearing a dust mask, use a palette knife or spoon to transfer each pigment to a small glass jar (baby food jars work great if you first boil them for 20 minutes to remove bacteria). Add distilled water. Put the cap on the jar and shake. You now have a pigment paste. Take the mask off, since there isn’t any more pigment dust to worry about.
Separate an egg yolk into another jar. Add about a teaspoon of distilled water and mix. To make egg tempera paint, mix about equal amounts of the egg mixture with pigment paste.
This is classic egg tempera of the sort that is used to make ikons (I’m pretty sure about that, but I am no expert on ikon painting). You can add other substances to it (oils, resins, etc.), but I suggest you learn to paint with just yolk, water, and pigment before you try to experiment with more complex mixtures.