Most Easter lilies
derive from the Lilium longiflorum species, although the
Madonna lily is actually the Lilium candidum species. The
L. longiflorum type is what growers call the "white
trumpet lily." Regardless, you'll want to pick one that has
several unopened flower buds to allow you to enjoy the blooms
for a longer time. Once in your home, Easter lilies prefer moderately cool temperatures. Recommended daytime temperatures are 60 to 65 degrees F with slightly cooler temperatures at night. Avoid placing your prize near drafts or excess heat or dry air from an appliance, heating duct, or fireplace. The lily will do best near a window in bright, indirect natural daylight. Try to avoid glaring, direct sunlight.
Be sure you don't kill your plant with the kindness of water. Water when the first inch or so of soil is dry to the touch. You can find this out by poking your finger down into the soil. If the pot is in a decorative pot or foil liner, be sure the pot has drainage holes to allow extra water to drain away from the plant's roots.
If you are really serious about prolonging your Easter lily's beauty, you'll want to remove the bright yellow pollen from the anthers on the blooms. But be careful. The pollen may stain the flower petals and anything else it touches. Taking away this pollen will extend the blooms.
After the blooms have faded, hold on to your horses. You can plant this symbol of purity outside in a sunny location. Good drainage is crucial for success, so raise the bed by adding good soil, peat moss, compost, rotted manures, etc. Then plant the bulb only 3 inches below ground level. Place another 3 inches of topsoil on top of the mound. Plant each bulb about 12-18 inches apart, and be sure to water as soon as you finish there. Your payoff will be next summer.
Be sure to add a few inches of mulch on the soil surface to help keep the soil cool. The mulch will also conserve moisture between watering. A great practice is to use "living mulch" instead of pine bark or pine needles, for example. This would be a low-growing, shallow-rooted complimentary planting such as vinca, violas, pansies, or some other low growing plant. That's good gardening.
Easter lily bulbs are surprisingly hardy if the ground is adequately mulched. But be sure to remove excess mulch in the spring to help them jump back up. You'll be taking part in the business of the "white gold" that started when the Japanese bombed Pearl Harbor. They had been the world's supplier of white lilies; but that's when their bulb shipping stopped and ours began.