The ideal worms for farming of any sort are called red wrigglers, and can usually be readily purchase from garden supply shops or fishing bait stores. They'll eat fruit and vegetable leavings along with eggshells easily, but should not be fed meat, dairy or salty foods. Some people "farm" red wrigglers as a source of dietary protein. Others may cultivate these worms for fishing bait, pet food or as a gardening tool, since the worms quickly devour vegetable and fruit wastes and transform them into rich fertilizer.
Select a plastic or metal container as your worm bin. It should be at least a foot deep, and have about 1 square foot of surface area for each pound of kitchen vegetable waste you expect the worms to devour each week. The container should also have an opaque, tight fitting lid.
Drill small holes in the sides and bottom of the container and in the lid for drainage and air circulation, and place the container on a tray to catch drips. A shallow cookie sheet works well for rectangular or square containers, while trays meant to catch plant drippings work well for round containers.
Run newspaper through a paper shredder or cut or rip it into thin strips. Pile the strips in your worm bin until it's at least two-thirds full. Then use the spray arm on a faucet, or a spray bottle, to dampen the newspaper until it's thoroughly moist but not soggy. Save out enough of this damp newspaper, in a separate container, to form a covering about 1 inch thick.
Mix in a few crushed eggshells, a few handfuls of outdoor garden soil, and some spent coffee grounds. Make sure the mixture is thoroughly mixed and not tamped down. Add your worms on top of this, toss in some scraps of vegetable waste, then spread the damp newspaper you saved out on top of everything. Fasten the lid tightly on your worm bin.
Continue adding vegetable waste as you produce it. Ideally the waste should be finely chopped or shredded; this helps the worms process it faster. Always bury the waste under at least an inch of bedding, rotating which part of the bin you bury it in each time.
Add more bedding as the worms slowly process it into fertilizer. Every few days, check to make sure that the bedding is still damp but not moist.
Harvest worms--or fertilizer--by burying food in one side of the bin. The worms will migrate to that side of the bin over the course of a few weeks. You can then either harvest the worms by scooping them out of the "full" side, or the fertilizer by scooping it out of the "empty" side. Always replace harvested fertilizer with fresh bedding.