Earthworms are easy. all u need is a wormbox and some good dirt plus trash and table scraps. Worked for me but didnt have much luck cuz i think they got out somehow.
Peat moss is better than dirt IME. Cornmeal is also a better food for earthworms. Make sure the medium they are being kept in is moist, but not saturated. Drains are very necessary. Dark and cool is another thing to make sure to maintain.