Cut the avocado open. Scoop out the seed with a spoon. Let the seed dry for a day or so. Remove the papery skin by gently rubbing it with a towel.
Place a single layer of paper towel in the bottom of the pot to keep the soil in the pot and let excess water drain. Fill the pot with fresh potting soil to within 2 inches of the top of the pot.
Put the seed in the pot with the rounded end up and the pointed end down. Plant the seed on its side if you can't distinguish between rounded and pointed ends. Cover with soil. Pat the soil down and water until the soil is thoroughly wet. Place in a sunny window. Don't let the soil completely dry out, but it shouldn't be soggy either.
Fertilize with half strength of a water soluble fertilizer once a month.
Keep the avocado in bright light.
Pinch out the top stem when the plant is 12 to 18 inches tall and has four to six leaves to force the plant to become bushier.
Follow the first two steps in the first section. Stick a toothpick into the seed in three places, equidistant around the seed and about a one-third of the way down the seed from the rounded top.
Place the seed and toothpicks on the rim of a glass. Fill the glass with water. Place in a sunny window.
Transplant into a pot with fresh soil. Bury the seed so it's just below the surface of the soil.