Obtain a supply of open-pollinated corn seed. You can order many varieties of open-pollinated corn from seed catalogs. You also may find local farmers who open-pollinate their corn and are willing to share or sell some of the seed.
Plant the seeds at least 200 feet from other varieties of corn, to prevent cross-pollination. If you work with just one small garden plot, plant just one variety each year to maintain the integrity of the strain.
Plant the seeds in several short rows instead of a few long rows, to make it easier for the corn to pollinate.
Leave the best ears on the stalks and allow them to dry. Save the kernels for planting future crops. Store them in the freezer; they can last for several years.