What is the proper way to prepare rhubarb as to not poison anyone? What parts of the plant is poisonous? and what general precautions should be done when making food involving rhubarb?
Use only the stalks; the leaves are poisonous (or at least toxic if eating in high quantity)
Cut up the stalks in chunks from the bottom up to the where it becomes green (to keep the result as pink as possible) and cook down with sugar and enjoy in a crumble or a pie (with strawberries).
I've ate raw stalk dipped in sugar when I was a kid.
Precautions for rhubarb gardening
Trim leaves from stalk immediately. Don't use stalks from frost bitten plants. Wash the stalks well. Children should be taught to eat only the rhubarb stalks, preferably under supervision